Pour buttermilk into a large bowl and submerge all chicken pieces, ensuring they are fully covered. Cover the bowl and refrigerate for at least 2 hours, preferably overnight, to allow the acid to break down muscle fibers and season the meat from the inside out.

Combine all-purpose flour, paprika, garlic powder, onion powder, salt, and black pepper in a shallow dish. Whisk thoroughly to ensure the spices are evenly distributed throughout the flour.

Preheat oven to 400 degrees F. Cut potatoes into wedges and toss with olive oil, garlic powder, salt, and pepper. Spread in a single layer on a baking sheet and place in the oven to roast while preparing the chicken.

Remove each piece of chicken from buttermilk and dredge thoroughly in the seasoned flour mixture. Heat oil to 350 degrees F in a deep skillet. Working in batches, carefully lower chicken into hot oil and fry for 12-15 minutes, turning halfway through, until coating is deep golden brown and internal temperature reaches 165 degrees F. Drain on paper towels.

Wash and tear lettuce, slice cucumber, halve cherry tomatoes, and thinly slice red onion. Arrange all ingredients on a serving plate or bowl. Add dressing just before serving to keep greens crisp.