Drain the fish well. Peel garlic and chop finely. Stir well with a mixer half of the capers, garlic, tuna and salad cream and season with salt and pepper.
Then puree the cream with a immerson blender finely.
Cut gherkins into thin slices. Fill tuna-cream into a piping bag with a large star tip and squirt some cream on each cracker. Garnish with the remaining capers, gherkins and the parsley.