For the tomato sauce, carefully fry the diced onions and the chopped garlic in the olive oil until golden. Add the tomato paste and a pinch of sugar and roast. Add the tomato cubes, bring to the boil and season. Finally add the chopped tarragon and season to taste.
Prepare the cannelloni according to the instructions on the packet. Dice the trout fillets and the salmon or pike fillet and season with salt, pepper, cayenne pepper and nutmeg. Pour the lime juice over it and puree with a dash of cream. Mix the fish puree with the remaining cream, eggs, chopped parsley and tarragon and thicken with breadcrumbs.
Pour the mixture into the cannelloni and place them in a lightly oiled baking dish. Spread the tomato sauce evenly over the cannelloni. Cook the cannelloni in a preheated oven at 180 ° C for about 15-20 minutes. Arrange the cannelloni with the sauce on pasta plates and serve immediately.