From The New Grocer
Leeks have a mild, onion-like taste. In its raw state, the vegetable is crunchy and firm. Leeks can be boiled, braised or steamed. Sliced leeks should be cooked for 5-7 minutes until tender but still firm. Whole small leeks should be cooked for 10-15 minutes until tender but still firm, top with a cheese sauce and then brown under a preheated grill for 5 minutes or until golden.