Place 1 lb chicken tenderloins in a bowl and pour 1 cup buttermilk over them. Cover and refrigerate to marinate for at least 1 hour.
Prepare three shallow dishes: in the first combine 1 cup all-purpose flour, 1 teaspoon salt, 1/2 teaspoon black pepper, 1/4 teaspoon garlic powder, and 1/4 teaspoon paprika; in the second beat the 2 large eggs; in the third place 1 cup panko breadcrumbs.
Remove the chicken from the fridge and gently shake off excess buttermilk; pat lightly with paper towels if very wet (do not remove all moisture).
Working one piece at a time, dredge a chicken strip in the seasoned flour, shake off excess, dip into the beaten eggs letting excess drip off, then press and roll in the panko breadcrumbs until evenly coated. Place coated strips on a plate or wire rack. Repeat with remaining strips.
Pour vegetable oil for frying into a deep fryer or large, heavy skillet to a depth that will allow frying (enough to partially or fully submerge the strips). Heat the oil to 350°F (175°C). If you do not have a thermometer, heat until the oil is shimmering and a small pinch of flour sizzles on contact.
Fry the chicken in batches without crowding the pan, turning once, until the coating is golden brown and the internal temperature of the thickest piece reaches 165°F, about 3–4 minutes per side depending on thickness. Adjust heat as needed to maintain ~350°F.
Transfer cooked chicken fingers to a paper towel–lined plate or wire rack to drain briefly. Serve hot.