A Beet, Caramelized Onion and Goat Cheese Sandwich, made fast if you plan ahead. (Bonnie Jo Mount/WASHINGTON POST)
Food and Dining Editor

Some nights, sandwiches seem like the easiest dinner possible — if you’re a meat eater and want to reach for the cold cuts. For vegetarians, a little more planning typically is in order. I’ve made sandwiches from combinations of raw or refrigerator-stable ingredients, such as a grilled “kimcheese” and one that layers thin slices of zucchini with radicchio and ricotta, but mostly I’m depending on leftovers.

An even better bet is to plan on those leftovers — that is, to get in the habit of making certain things in advance so you have them around to draw from. It’s especially helpful, obviously, with ingredients that take a long time to cook.

Two such examples presented themselves to me recently when I encountered a delicious appetizer made by chef Cedric Maupillier at Mintwood Place in Adams Morgan. It’s a roasted beet, goat cheese and onion “mountain pie,” a white-bread sandwich he presses in a pie iron and cooks in the wood oven. (Traditionally it goes right in campfire embers, hence the name.)

Beets and caramelized onions can take up to an hour to make, but I’ve gotten in the habit of preparing batches of each every week or two to put on salads, pizza and more. When I scrounged around in my fridge recently for dinner ideas, there they were, ready for me to combine with a schmear of soft goat cheese between slices of sprouted whole-grain bread. At home, I have neither wood oven nor pie iron, but a skillet on the stove top helps me turn the lot into a simply grilled sandwich.

In the case of the beets, a supermarket shortcut is available: cooked and refrigerated baby beets in the produce section. They’re a whole lot more expensive than fresh ones, but sometimes — when I haven’t done the prep work myself — I’m willing to pay for the convenience. So far, I’m on my own when it comes to the onions.