Crispy Pork Cutlets with Tonnato Sauce

Preheat oven to 200°F. Process 1/2 cup oil, caperberries, anchovies, lemon zest and juice, and 1/4 teaspoon pepper in a food processor until almost smooth, about 1 minute. Add tuna; process until smooth and thick, about 2 minutes, scraping downsides as needed. Transfer to a bowl; stir in 1/2 cup water until smooth. Cover and refrigerate until ready to use.

Sprinkle pork evenly on both sides with salt and remaining 1/4 teaspoon pepper. Place flour, eggs, and panko in 3 separate wide, shallow bowls. Working with 1 cutlet at a time, dredge in flour, and shake off excess. Dip in eggs; let excess drip off. Dredge in panko to coat. Place on a plate.

Heat 1/2 cup oil in a 12-inch skillet over medium. Working with 1 or 2 cutlets at a time, cook in hot oil until golden brown, crisp, and cooked through, 2 to 3 minutes per side. Transfer to a baking sheet lined with paper towels; sprinkle lightly with salt to taste, and place in preheated oven to keep warm. Repeat with remaining cutlets, adding remaining 1/4 cup oil to skillet after cooking 2 cutlets.

Divide cutlets among 4 plates; spoon about 1/3 cup tonnato sauce over each cutlet. Top evenly with parsley and onion. Garnish with additional caperberries and pepper. Serve with lemon wedges and remaining tonnato sauce.