Begin by using a meat mallet to flatten the chicken tenderloin pieces. The chicken fries much more evenly (and tastes better!) when you flatten it first. (I do this by placing tenderloins into a large/durable ziploc bag – then close the bag and use a meat mallet to flatten the pieces).
In a bowl or wide dish, combine wet marinade ingredients (buttermilk and spices). Place chicken in buttermilk marinade and let sit for 30 minutes – 4 hours).
When ready to cook, begin by getting your station ready. Get a large baking sheet and line it with paper towels. Set next to stove.
Pour oil into large heavy-bottom pot until it comes up 3-4 inches on the sides of the pot. Have tongs ready and begin to heat the oil to 325 degrees in a large pot. Heat oil on medium-high heat for several minutes, until beginning to sizzle.
Meanwhile, prep the dry ingredients in wide, flat dish. Whisk all the dry ingredients minus the oil.
Remove pieces of the wet chicken from the marinade, being careful to shake off large amounts of the buttermilk.
Dredge the wet chicken pieces in the flour mixture, being careful to cover both sides very well.
Using tongs, place chicken, 1 piece at at time, into the large pot with the oil. If oil is ready, chicken should sizzle. Carefully watch to make sure oil isn’t popping. Cook 3-4 in a pot at once, leaving room around each to keep from crowding.
Cook chicken for 4-5 minutes on first side, then 3-4 minutes on the second side (flipping partway through). Continue frying until chicken is cooked through.
Once cooked, remove from oil and set onto paper towel lined baking sheet. Let rest 5 mintues before assembling into sandwich. (I usually test 1-2 pieces of chicken for done-ness by cutting a small slit into the center to make sure it's cooked through)
Lightly sprinkle a pinch of salt over the warm chicken when it is resting on the paper towel lined baking sheet.
In a small tupperware or mason jar, use a fork to whisk together all the spread ingredients. Chill until ready to serve.
If desired, toast one side of your brioche buns (flat side down) on a warm pan.
Build your sandwich by slathering the Garlic Spread on the brioche, stacking with a handful of shredded iceberg lettuce, and then topping with a warm piece of chicken.