For the fennel and mince gratin, clean and wash the fennel, cut into pieces and cook in vegetable soup until soft. Fry the onions with the minced meat in oil, add salt and pepper.
Add the tomato paste, pour some vegetable soup and simmer for about 3 minutes. Mix with the fennel, put in a baking dish and cover with the cheese.
Put in the preheated oven and bake at 220 °C for about 15 minutes.
The fennel and mince gratin can be made with mixed or with mince of one variety. Depending on your taste. A few cubes of bacon give it some more spice.