1/2 cup mayonnaise
2 1/2 tablespoons chopped fresh dill
2 tablespoons drained capers
2 tablespoons chopped fresh chives
2 tablespoons finely chopped cornichons or dill pickles plus 1 tablespoon pickle juice from jar
1 1/4 cups panko (Japanese breadcrumbs)
1 large egg
1 1/2 pounds 3/4-inch-thick halibut fillets, cut into 3×3/4-inch strips
3 tablespoons olive oil, divided
Mix first 5 ingredients in bowl. Season with pepper. Cover and chill tartar sauce. Spread panko on plate. Whisk egg in small bowl. Sprinkle fish with salt and pepper. Working in batches, coat fish in egg. Coat in panko; shake off excess.
Heat 1 1/2 tablespoons oil in large nonstick skillet over medium heat. Add half of fish and cook, turning often, until fish is opaque in center and golden on all sides, about 4 minutes total. Transfer to 2 plates; cover to keep warm. Repeat with remaining oil and fish. Spoon tartar sauce alongside.