About 6 cups vegetable oil
2 racks baby back ribs (about 1 pound each), cut into ribs
1/3 cup all-purpose flour
3 large eggs, lightly beaten
1 1/2 to 1 3/4 cups panko (Japanese bread crumbs)
For mustard sauce:
1/2 cup sour cream
2 tablespoons mayonnaise
1 Kirby cucumber, coarsely grated
2 tablespoons Dijon mustard
Preheat oven to 200°F.
Heat 3/4 inch oil to 325°F in a deep 12-inch skillet over medium heat.
Meanwhile, season ribs with 3/4 teaspoon salt and 1/2 teaspoon pepper. Put flour, eggs, and panko in 3 separate shallow bowls. Dredge ribs in flour, then coat with egg, letting excess drip off, and panko.
Fry ribs in batches, turning once, until golden brown and cooked through, 7 to 8 minutes per batch. Transfer first batch to a paper-towel-lined baking sheet and keep warm in oven. (Return oil to 325°F between batches.)
Make sauce while ribs fry:
Stir together sauce ingredients. Serve ribs with sauce.