Place the gnocchi ingredients into a mixing bowl and knead with enough eggs into non-stick dough. Transfer onto a lightly floured surface, divide and roll into cigars, chop into gnocchi bites and chill. In a separate bowl marinade the tomatoes with the remaining marinating ingredients. Brush the salmon lightly with the horse radish and roll in the pepper corns. Cook the tuna to the desired temperature in melted butter over moderate heat. Cook the gnocchi in boiling salted water and toss with the marinated tomatoes. Serve the tuna over the marinated gnocchi.