Crispy Onion Chicken Sandwich (Printable)

Buttermilk-marinated fried chicken topped with crispy onions and garlic aioli on toasted brioche buns.

# What You'll Need:

→ Chicken & Marinade

01 - 4 boneless, skinless chicken thighs
02 - 1 cup buttermilk
03 - 1 teaspoon garlic powder
04 - 1 teaspoon paprika
05 - 1/2 teaspoon salt
06 - 1/2 teaspoon black pepper

→ Breading

07 - 1 cup all-purpose flour
08 - 1/2 cup cornstarch
09 - 1 teaspoon smoked paprika
10 - 1 teaspoon salt
11 - 1/2 teaspoon ground black pepper

→ Crispy Onions

12 - 1 large yellow onion, thinly sliced
13 - 1/2 cup all-purpose flour
14 - 1/2 teaspoon salt
15 - 1/2 teaspoon black pepper
16 - Vegetable oil for frying

→ Aioli

17 - 1/2 cup mayonnaise
18 - 1 large garlic clove, minced
19 - 1 tablespoon fresh lemon juice
20 - 1/2 teaspoon Dijon mustard
21 - Salt and black pepper to taste

→ Assembly

22 - 4 brioche buns, sliced
23 - Butter for toasting buns (optional)
24 - Lettuce leaves (optional)

# Directions:

01 - Whisk together buttermilk, garlic powder, paprika, salt, and black pepper in a bowl. Submerge chicken thighs ensuring complete coating. Cover and refrigerate for 30 minutes minimum or up to 4 hours.
02 - Combine flour, cornstarch, smoked paprika, salt, and black pepper in a shallow dish and set aside.
03 - Toss sliced onions with flour, salt, and black pepper in a separate bowl until evenly coated.
04 - Heat 1 inch of vegetable oil in a large skillet to 350°F. Working in batches, fry onions for 2-3 minutes per batch until golden and crispy. Transfer to paper towels to drain.
05 - Remove chicken from marinade, allowing excess liquid to drip off. Coat each thigh thoroughly in breading mixture, pressing gently to adhere.
06 - Fry breaded chicken in the same hot oil for 5-7 minutes per side until golden brown and cooked through. Transfer to a wire rack or paper towels to drain excess oil.
07 - Combine mayonnaise, minced garlic, lemon juice, Dijon mustard, salt, and pepper in a small bowl and mix thoroughly.
08 - Optional step: butter brioche buns and toast in a skillet over medium heat until golden brown on both sides.
09 - Spread aioli on both bun halves. Layer with lettuce if desired, fried chicken thigh, generous amount of crispy onions, and close with top bun.

# Expert Tips:

01 -
  • The buttermilk marinade keeps the chicken so tender you barely need to chew, and the cornstarch in the breading gives it an extra crackly crust.
  • Crispy onions add a sweet, savory crunch that makes every bite feel like a celebration.
  • The garlicky aioli pulls everything together with just enough tang to balance the richness.
  • It feels like a restaurant splurge but comes together in your own kitchen with ingredients you probably already have.
02 -
  • Don't skip the marinating time, the buttermilk needs at least 30 minutes to tenderize the chicken or it won't be as juicy.
  • Keep the oil temperature steady at 350 degrees F, too hot and the crust burns before the chicken cooks through, too cool and it absorbs oil and turns greasy.
  • Fry the onions first so you can use the same oil for the chicken, it saves time and adds extra flavor to the crust.
  • Let the fried chicken rest on a wire rack instead of paper towels, it keeps the bottom from getting soggy while the steam escapes.
03 -
  • Use a thermometer to check the oil temperature before frying, guessing leads to soggy or burnt chicken every time.
  • Press the breading firmly onto the chicken with your fingertips so it forms a thick, even crust that won't fall off in the oil.
  • Let the fried chicken rest for a full minute before assembling the sandwiches, it gives the crust time to set and stay extra crispy.
  • If your onions aren't crisping up, your oil isn't hot enough, bump the heat and try again with a fresh batch.
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