Peel and crush the garlic. Peel the onions and slice. Slice the leek and the fennel. Sauté it all in olive oil until brown, and then add the crabs, allowing them to turn red. Flambé with the pastis.
Using a rolling pin, crush the crabs, pour over the white wine and allow to reduce. Add 500 ml of water, the fish soup, tomatoes and saffron. Cook for 1 hour