Roast the onion and possibly the garlic in a little olive oil until golden, cut the fennel into bite-sized pieces and add, add the tomato paste and roast briefly, deglaze with the white wine and stock, add the tomatoes, season with salt, pepper and sugar (caution, will be reduced) and Let simmer until the fennel is nice and soft. If necessary, add a little vegetable stock, season to taste, done!