Leftovers become veggie sandwich

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 Washington. 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.

Beet, Caramelized Onion and Goat Cheese Sandwiches

Servings: 4

A quick-pickled beet lends a welcome tartness to offset the rich goat cheese and sweet onions. To save time, look for cooked, vacuum-packed beets in the supermarket produce section. The caramelized onions can be refrigerated for up to 2 weeks. The beets can be refrigerated for up to 1 week. From Washington Post Food editor Joe Yonan, author of the upcoming “Eat Your Vegetables: Bold Recipes for the Single Cook” (Ten Speed Press, August 2013).

1 tablespoon olive oil

2 large yellow onions (1 3/4 pounds total), thinly sliced

1/4 teaspoon sea salt, plus more to taste

Water (optional)

4 small to medium beets (about 1 pound total), stemmed and well scrubbed

1 tablespoon red wine vinegar

1 teaspoon honey

4 ounces soft, spreadable goat cheese

8 slices low-sodium whole-grain bread, such as Ezekiel 4:9 brand

2 teaspoons canola oil

Heat the olive oil in a large cast-iron or other heavy skillet over medium heat. Add the onions and cook, tossing with tongs or a spatula, until they wilt and start to brown. Sprinkle with the salt, toss and reduce the heat to the lowest possible setting. Cook, stirring very occasionally, until the onions are deeply golden brown, soft and sweet, up to an hour or more. (If they start to dry out during cooking, stir in a few tablespoons of water at a time to keep them moist.) Transfer the onions to a bowl to cool, and wipe out the skillet.

Set a steamer basket in a medium saucepan filled with an inch or two of water, over medium heat. Bring the water to a boil, then reduce the heat so the water is gently bubbling and add the beets. Cover and steam until barely tender when pierced with a fork, 25 to 40 minutes (depending on their size). Remove from the heat, cool slightly, and slip off the skins under running water.

Cut the beets into 1/2 -inch-thick slices. Place them in a medium bowl and toss gently to coat with the vinegar and honey.

Spread the goat cheese on one side of 4 bread slices. Top each with the sliced beets, caramelized onions and one of the remaining 4 bread slices. Press gently to compress each sandwich.

Brush the skillet with the canola oil and heat over medium-high heat. Once the oil starts to shimmer, lay the sandwiches in the skillet, working in batches if necessary. Cook, pressing gently with a spatula from time to time, until the undersides are golden brown, about 2 minutes. Repeat to brown the second sides. Serve warm.

Per serving: 420 calories, 17 g protein, 63 g carbohydrates, 13 g fat, 5 g saturated fat, 15 mg cholesterol, 330 mg sodium, 12 g dietary fiber, 18 g sugar