Tasting like a cross between artichoke, celery and salsify, this delicious vegetable is very popular in France, Italy and Spain. The cardoon resembles a giant bunch of wide, flat celery. Cardoons can be found from midwinter to early spring. Look for stalks that are firm and have a silvery gray-green color. Refrigerate in a plastic bag up to 2 weeks. To prepare, remove tough outer ribs. Cut the inner ribs into the size indicated in the recipe and soak in acidulated water to prevent browning. Cardoons can be boiled, braised or baked. Precooking about 30 minutes in boiling water is suggested in many recipes. Though high in sodium, cardoons are a good source of potassium, calcium and iron.