Wash the plaice fillets and dab dry. Steam 2 fillets in slightly salted water for 2-3 minutes until the fish flesh is firm.
Season the other fillets with salt and pepper, pull them through the whisked egg and then turn them into breadcrumbs. Fry in hot oil for 2-3 minutes on each side.
Rinse shrimps in a sieve and drain well. Stir the créme fraiche and mayonaise until smooth. Season to taste with salt and paprika powder.
Toast white bread. Top with lettuce leaves, the plaice fillets and shrimps. Add mayo cream and caviar. Garnish with lemon.