Crispy Onion Chicken Sandwich

Featured in: Weeknight Dinners

This mouthwatering sandwich combines tender buttermilk-marinated chicken thighs fried until golden, crispy fried onions, and a homemade garlic aioli. The chicken marinates for 30 minutes to 4 hours, then gets dredged in a flavorful breading before frying. Onions are breaded separately for extra crunch. Assembly is simple: spread aioli on toasted brioche, layer with lettuce, chicken, and onions. Ready in 50 minutes total.

Updated on Sun, 18 Jan 2026 15:28:00 GMT
Juicy buttermilk-marinated fried chicken topped with golden crispy onions and creamy aioli in a toasted brioche bun. Save
Juicy buttermilk-marinated fried chicken topped with golden crispy onions and creamy aioli in a toasted brioche bun. | quantumgrill.com

My favorite spatula broke mid-flip the first time I tried frying chicken thighs at home, and I had to MacGyver a wooden spoon situation that somehow worked. That chaotic evening taught me more about heat control and timing than any tutorial ever could. The onions burned slightly because I got distracted, but the sandwich still disappeared in minutes. Now I keep backups of every tool and actually set timers. This recipe is my redemption arc in sandwich form.

I made these sandwiches for a small backyard gathering last summer, and my neighbor asked if I'd catered them. The pile of crispy onions in the center of the table vanished before the chicken even finished frying. Someone suggested I open a food truck, which was flattering but unrealistic given my tiny kitchen. That night convinced me that homemade fried chicken doesn't have to be intimidating. It just needs confidence and a good thermometer.

Ingredients

  • Boneless, skinless chicken thighs: Thighs stay moist and tender through the frying process, and their slightly irregular shape creates extra crispy edges.
  • Buttermilk: The acidity tenderizes the meat while adding subtle tang; if you don't have it, mix milk with a tablespoon of lemon juice and let it sit for five minutes.
  • Garlic powder and paprika: These build a savory base in the marinade without overwhelming the chicken's natural flavor.
  • All-purpose flour and cornstarch: Cornstarch makes the breading shatteringly crisp, a trick I learned from a Korean fried chicken recipe.
  • Smoked paprika: Adds a subtle smoky depth that makes people ask what your secret ingredient is.
  • Yellow onion: Slice them thin and uniform so they fry evenly; inconsistent slices mean some burn while others stay limp.
  • Mayonnaise: The aioli base; use full-fat for the best texture and richness.
  • Fresh garlic clove: Minced fine or grated on a microplane, it brings the aioli to life in a way jarred garlic never does.
  • Lemon juice: Brightens the aioli and cuts through the richness of the fried chicken.
  • Dijon mustard: A small amount adds complexity and helps emulsify the aioli.
  • Brioche buns: Soft, slightly sweet, and sturdy enough to hold everything without falling apart in your hands.
  • Vegetable oil: Use something with a high smoke point like canola or peanut oil for frying.

Instructions

Marinate the chicken:
Whisk the buttermilk with garlic powder, paprika, salt, and pepper until smooth, then submerge the chicken thighs completely. Cover the bowl and refrigerate for at least 30 minutes, though a few hours makes the meat even more tender.
Prepare the breading:
Combine flour, cornstarch, smoked paprika, salt, and pepper in a shallow dish, mixing thoroughly so the spices distribute evenly. The cornstarch is what gives you that audible crunch when you bite in.
Coat the onions:
Toss thinly sliced onions with flour, salt, and pepper until every strand is lightly dusted. Shake off excess flour before frying or it will clump and burn.
Fry the onions:
Heat about an inch of oil to 350°F and fry the onions in small batches, stirring occasionally, until golden and crisp, about 2 to 3 minutes. Transfer immediately to paper towels and sprinkle with a pinch of salt while they're still hot.
Bread the chicken:
Pull each thigh from the marinade, let the excess buttermilk drip off, then press it firmly into the breading mixture on both sides. Let the breaded chicken rest on a plate for a few minutes so the coating adheres better during frying.
Fry the chicken:
Carefully lay each thigh into the hot oil and fry for 5 to 7 minutes per side until deep golden brown and the internal temperature reaches 165°F. Don't crowd the pan or the temperature will drop and the coating will turn soggy instead of crispy.
Make the aioli:
Whisk together mayonnaise, minced garlic, lemon juice, Dijon mustard, salt, and pepper in a small bowl until smooth. Taste and adjust the seasoning; it should be punchy and bright.
Toast the buns:
Butter the cut sides of the brioche buns and toast them in a skillet over medium heat until golden and fragrant. This step is optional but adds a buttery richness that's worth the extra minute.
Assemble the sandwiches:
Spread aioli generously on both halves of each bun, layer with lettuce if you like, add a fried chicken thigh, then pile on a generous handful of crispy onions. Press the top bun down gently and serve immediately while everything is still warm.
Crispy Onion Chicken Sandwich served on a soft bun with crunchy fried onions and fresh lettuce. Save
Crispy Onion Chicken Sandwich served on a soft bun with crunchy fried onions and fresh lettuce. | quantumgrill.com

The first time I nailed this sandwich, I texted a photo to my sister, and she replied with three fire emojis and a demand for the recipe. We ended up on a video call while she made it that same weekend, and hearing her surprised laugh when she bit into it made me feel like I'd passed on something valuable. Food has this way of connecting people across distance, even when it's just a fried chicken sandwich. That night turned into a monthly tradition where we cook the same recipe and video chat over dinner.

Making It Your Own

Add a few dashes of hot sauce to the aioli if you want heat without changing the breading, or mix cayenne directly into the flour for a spicier crust. I've tried both, and the aioli route gives you more control over each bite. Pickled jalapeños or a tangle of coleslaw also work beautifully as toppings. Swap the brioche for potato buns if you want something a little less sweet. The beauty of this sandwich is how adaptable it is to whatever's in your fridge.

Timing and Prep Tricks

You can marinate the chicken the night before and keep it in the fridge, which actually improves the flavor. The aioli also tastes better after sitting for an hour, so make it early and let the garlic mellow. Fry the onions first and keep them in a low oven to stay warm and crisp while you cook the chicken. If you're feeding a crowd, bread all the chicken at once and fry in batches, keeping finished pieces on a wire rack in a 200°F oven. Toasting the buns right before assembly ensures they stay warm and buttery.

Storage and Leftovers

Fried chicken keeps in the fridge for up to three days, but reheating it in a 375°F oven for about 10 minutes brings back most of the crispiness. The onions lose their crunch quickly, so store them separately in an airtight container and re-crisp them in a hot oven for a few minutes. Aioli lasts about a week in the fridge and actually gets better as the flavors meld. Don't assemble sandwiches ahead of time or the buns will get soggy.

  • Reheat chicken in the oven, not the microwave, to preserve the crust.
  • Store crispy onions separately and refresh them in a hot oven before serving.
  • Aioli can be made up to a week in advance and stored in an airtight container.
Golden fried chicken thighs stacked with crispy onions on a buttered brioche bun, drizzled with garlic aioli. Save
Golden fried chicken thighs stacked with crispy onions on a buttered brioche bun, drizzled with garlic aioli. | quantumgrill.com

This sandwich has become my go-to when I want to impress someone without pretending I'm a chef. It's messy, satisfying, and tastes like effort even though the technique is straightforward once you've done it a few times.

Common Questions

Can I prepare the chicken ahead of time?

Yes, marinate the chicken for up to 4 hours in advance. You can also bread the chicken and refrigerate it for a few hours before frying for convenience.

How do I keep the fried components crispy?

Drain fried chicken and onions on paper towels immediately after cooking. Assemble sandwiches just before serving to maintain crispness. Toasting the brioche buns also prevents them from absorbing moisture.

What oil temperature is best for frying?

Maintain oil at 350°F (175°C). Use a thermometer for accuracy. This temperature ensures golden, crispy exteriors while cooking the chicken through without burning.

Can I use chicken breasts instead of thighs?

Yes, chicken breasts work well but may dry out more easily. Pound them to even thickness and reduce cooking time to 4-5 minutes per side to prevent overcooking.

How should I store leftovers?

Store fried chicken and onions separately in airtight containers for up to 3 days. Reheat in a 350°F oven for 10-15 minutes to restore crispness. Keep aioli refrigerated for up to 5 days.

What are good side dish pairings?

Serve with pickles, coleslaw, or fresh slaw for added crunch and acidity. French fries, sweet potato fries, or a light salad complement the richness of the sandwich beautifully.

Crispy Onion Chicken Sandwich

Buttermilk-marinated fried chicken, crispy onions, and garlic aioli stacked on toasted brioche buns.

Prep Time
25 min
Time to Cook
25 min
Overall Time
50 min
Recipe by Evan Clark


Skill Level Medium

Cuisine Type American

Makes 4 Portions

Dietary Details None specified

What You Need

Chicken & Marinade

01 4 boneless, skinless chicken thighs
02 1 cup buttermilk
03 1 teaspoon garlic powder
04 1 teaspoon paprika
05 0.5 teaspoon salt
06 0.5 teaspoon black pepper

Breading

01 1 cup all-purpose flour
02 0.5 cup cornstarch
03 1 teaspoon smoked paprika
04 1 teaspoon salt
05 0.5 teaspoon ground black pepper

Crispy Onions

01 1 large yellow onion, thinly sliced
02 0.5 cup all-purpose flour
03 0.5 teaspoon salt
04 0.5 teaspoon black pepper
05 Vegetable oil for frying

Aioli

01 0.5 cup mayonnaise
02 1 large garlic clove, minced
03 1 tablespoon lemon juice
04 0.5 teaspoon Dijon mustard
05 Salt and pepper to taste

Assembly

01 4 brioche buns, sliced
02 2 tablespoons butter for toasting buns
03 Lettuce leaves

How to Make

Instruction 01

Prepare buttermilk marinade: Whisk together buttermilk, garlic powder, paprika, salt, and black pepper in a bowl. Add chicken thighs and coat thoroughly. Cover and refrigerate for 30 minutes to 4 hours.

Instruction 02

Mix breading mixture: Combine flour, cornstarch, smoked paprika, salt, and black pepper in a shallow dish.

Instruction 03

Coat onions: Toss sliced onions with flour, salt, and black pepper in a separate bowl until evenly coated.

Instruction 04

Fry onions: Heat 1 inch of vegetable oil in a large skillet to 350°F. Working in batches, fry coated onions for 2-3 minutes until golden and crispy. Drain on paper towels.

Instruction 05

Bread chicken: Remove chicken from marinade, allowing excess buttermilk to drip off. Dredge each thigh in breading mixture, pressing gently to ensure coating adheres.

Instruction 06

Fry chicken: Fry breaded chicken in the same hot oil for 5-7 minutes per side until golden brown and cooked through. Transfer to wire rack or paper towels to drain.

Instruction 07

Prepare aioli: Combine mayonnaise, minced garlic, lemon juice, Dijon mustard, salt, and pepper in a small bowl.

Instruction 08

Toast brioche buns: Butter both sides of brioche buns and toast in a skillet over medium heat until golden brown.

Instruction 09

Assemble sandwich: Spread aioli on both sides of toasted buns. Layer with lettuce, fried chicken thigh, generous mound of crispy onions, and top with bun half.

Tools You'll Need

  • Mixing bowls
  • Large skillet or deep fryer
  • Tongs
  • Wire rack or paper towels
  • Knife and cutting board
  • Shallow dish for breading

Allergy Details

Always check every component for allergens. If unsure, ask a specialist.
  • Contains eggs in mayonnaise
  • Contains wheat in all-purpose flour and brioche buns
  • Contains milk in buttermilk and butter
  • Contains mustard in Dijon mustard aioli component
  • Brioche buns may contain soy or additional allergens; verify labels

Nutrition Details (each serving)

Nutrition data is informative only. Don't use as medical guidance.
  • Calorie Count: 670
  • Total Fats: 32 g
  • Carbohydrates: 61 g
  • Proteins: 32 g