For family and/or friends you have over for dinner, you can't go wrong with leeks au gratin.
Here's an easy yet appetizing dish that's a favorite with my family and our dinner guests. To make leeks au gratin, wash 6 leeks thoroughly, cut off the roots and the tough top leaves, and slice the vegetables lengthwise (or chop them into bite-sized chunks) into a skillet. Add just enough boiling water to keep the pieces from sticking, cover the pan, and let them simmer until they're tender, about 15 minutes.
Now, arrange the cooked leeks in a shallow baking dish and sprinkle them with 2 cups of freshly grated cheddar or Italian cheese. Add sea salt (or powdered kelp, if you can find it at an Oriental market or natural foods store) and pepper to taste, then pop the casserole into a low oven — about 300°F, but keep an eye on it — until the cheese melts.
For a heartier dish, try adding tomato wedges, green olives, tofu, or cooked ham, or perhaps simmering a few stalks of celery with the leeks.