Peel the onion, clean the zucchini, carrots and peppers. Cut the vegetables into very fine, small cubes and steam them in hot olive oil for about 5 minutes, season with plenty of salt and pepper. Then put the vegetables in a bowl and let them cool. Then mix well with sour cream and cheese. Pour the mixture into a freezer bag, cut off one corner, fill the cannelloni with it and place in a baking dish.
Heat the rest of the olive oil. Peel and finely chop the garlic or press and add to the olive oil, sauté briefly and then deglaze with the tomatoes and simmer gently for 5 minutes. Then stir in tomato paste, herbs and spices and season to taste.
Pour the tomato sauce over the cannelloni, sprinkle with parmesan and bake everything in a preheated oven at 160 ° C (hot air) for about 30 minutes.
Also tastes delicious with other vegetables, e.g., mushrooms, celery or eggplant.