Peel the kohlrabi and cut into sticks. Peel the carrots and cut into slices with the zucchini. Halve the pepper, clean, wash, core and cut into large cubes.
Preheat the oven to 200 ° C and grease a mold (30 cm). Heat two tablespoons of butter, add the vegetables and sauté. Add the tomatoes and tomato paste and bring to the boil. Season with salt, pepper and sugar and place in a mold.
Drain the mozzarella well, cut into slices and spread on the vegetables. Put the casserole in the oven and cook for about 20-30 minutes. Spread the rest of the butter on top in dots, let it melt and serve.
Fresh baguette tastes good with it.
Those who like it spicier can replace the mozzarella with hard cheese. If you are in a hurry, replace the fresh vegetables with a frozen vegetable mix.