Fennels can be kept for 3 weeks in the refrigerator, yet once washed and cut, they can be kept for 4 days. To clean them, you must remove the green beard and dark outer leaves and wash them. You can eat them raw and juiced, or slice them thinly and cook them in a pan. You can also boil or steam them for 15 minutes or, if you prefer, cut them into thicker slices, brush them with oil and bake them in the oven at 200° for 30 minutes. The green part can be used for sautéed vegetables or soups.