Wheatgrass. Photo: oklo, Flickr
To make green mashed potatoes (that taste exactly the same as regular potatoes): Stir in half a cup of green peas that you've puréed with a tablespoon of milk. If you use frozen peas, they should be defrosted but don't need to be cooked.
Green bread crumbs for chicken: In a food processor, pulse 4 slices of toast with 1/2 cup chopped parsley until you've got, yes, green crumbs. Toss this mixture together with 4 ounces grated fresh Parmesan and 1 crushed garlic clove.
Speaking of garlic and Parmesan, don't forget pesto! In addition to its usual function as a pasta sauce, it too makes a great coating for chicken and fish. Or make green garlic bread with it.
And speaking of pasta, this is definitely the time to serve the spinach variety.
Isn't there a bottle of green crème de menthe way, way back in your liquor cabinet? Make a Shamrock Shake: 1 cup milk, 1 cup vanilla ice cream, and crème de menthe to taste.
Even if you never drink it, wheatgrass juice is a startlingly bright, neutral-tasting, fabulously healthy natural colorant. Buy a couple of ounces to add to rice, cooked pasta, mayonnaise, cream cheese, dips... You can even add a few drops to vanilla pudding or sugar cookie dough without noticeably changing the taste.
It's not exactly Irish, but guacamole is green, and there's no reason it can't be served at supper along with crudités or tortilla chips.
Although Key lime pie is one of the easiest, best desserts around, it's not especially green. But it can be if you top it with thin-sliced kiwis, especially if you use three kiwi rounds to form shamrocks. Add a shred of kiwi to make a stem.
Even if you don't like to cook with green food coloring, adding a few drops to the toilets in your house makes a lovely St. Patrick's surprise. It won't stain the toilet, either!