Drain the tuna in a sieve. Wash, clean and finely dice the tomato. Wash parsley, shake dry and chop coarsely, except for something to garnish. Halve the capers.
Finely puree the tuna and crème fraîche in a tall beaker. Season to taste with salt, pepper and lemon juice. Stir in capers, tomato and parsley. Spread the tuna and tomato cream on bread. Garnish with parsley.