Blanch the zucchini whole for 2 minutes. Then cut in half and scrape out the seeds with a spoon. Soak the roll with the crust in the milk.
Gently squeeze the bread roll with a fork and place in a bowl. Add the drained canned tuna and 1 tablespoon of tuna oil. Add 2 tablespoons of chopped parsley and the finely chopped clove of garlic with salt and pepper to the mixture. Mix everything well and pour into the halved and hollowed zucchini.
Cut the tomato into eighths, add the inner flesh of the zucchini and add 250 ml liters of vegetable stock to the zucchini halves placed in an ovenproof dish. Cook uncovered at 200 degrees top / bottom heat for 25-30 minutes.
Puree the sauce with the vegetables and thicken with 1 tablespoon crème fraiche. This goes well with rice or potatoes.