Place a 12-inch cast-iron skillet in the oven. Preheat oven to 425 degrees F. For aioli: In a small bowl whisk together mayonnaise, fresh cilantro, lemon juice, garlic, cayenne, and a 1/8 tsp. salt. Cover and chill until serving time.
Season fish with 1/4 tsp. salt and 1/4 tsp. black pepper. Place in a large resealable plastic bag. In a small bowl whisk together the buttermilk and hot pepper sauce; pour over fish. Seal bag; set in a bowl. Chill 20 minutes.
Place cornstarch in a shallow dish; add 1/8 tsp. salt and 1/8 tsp. black pepper. In a second shallow dish lightly beat the eggs. In a third shallow dish combine the lemon zest, panko, dried cilantro, garlic powder, and 1/2 tsp. salt.
Drain fish, discarding any remaining marinade. Gently dip fish in cornstarch to coat, then dip in eggs to moisten. Dip in panko mixture to coat. Transfer to a tray or baking sheet.
Carefully remove the skillet from the oven; add olive oil. Carefully arrange fish sticks in skillet. Bake 10 minutes or until browned on the bottom. Turn and bake 8 to 10 minutes more (until fish flakes when tested with a fork and sticks are golden). Remove to paper towels to drain; let stand 5 minutes. Drizzle with additional lemon juice; serve with aioli.