Smart Saving: 9 Tips for Using Leftovers

Judging the interior temperature of reheated leftovers such as lasagna or a casserole can be difficult. To avoid serving leftovers that are tepid at the center, try this trick.
Before taking the casserole out of the oven, poke the center with the blade of a butter knife or dull dinner knife, and leave it in place for 15 to 30 seconds. Remove the knife and then touch the side of the blade very gently to the back of your hand. If the metal is hot, so, too, is the center of the casserole.

I did a lot of testing to determine the best way to heat a frozen casserole, and I found that the simplest method was actually the best— just put your frozen casseroles straight into a cold oven without defrosting. This method allowed the casserole to defrost gently as the oven came to temperature. Defrosting the casserole before baking took longer without giving better results, and putting a frozen casserole in a hot oven resulted in casseroles with bubbling tops over icy centers.

After a big weekend breakfast, there are inevitably a few uneaten pancakes or slices of French toast. Instead of discarding the leftovers, try this method for saving them and reheating them later.
1. Layer parchment paper between the cooked French toast slices or pancakes, wrap in plastic wrap and then in aluminum foil, and store in the freezer.
2. To reheat, unwrap and heat the French toast or pancakes for 10 to 12 minutes on a baking sheet in a 350-degree oven and serve with hot maple syrup. The breakfast treats can also be reheated in a toaster oven.

Making a large batch of soft-cooked eggs for the week is super convenient, but reheating them once they’ve been refrigerated can be a little tricky. One quick method is to place the cold egg(s) in a bowl—or, if taking your breakfast on the go, a food storage or deli container—and fill the vessel with hot water. Let sit for 3 minutes, drain, and serve.

For leftover rice that tastes just as fluffy and moist as a fresh-made pot, try this method.
Fill a saucepan with ½ inch of water. Place a steamer basket lined with a damp coffee filter in the pan. Add leftover rice; cover and cook until heated through, about 5 minutes. Fluff with a fork and serve.

Freshly cooked polenta has a terrific creamy texture, but leftovers cooled in the refrigerator turn thick and stiff. To restore your leftover polenta to its original creamy state, try the following technique: using quick pulses, process the cold polenta in a food processor, adding a few tablespoons of warm water for every cup of cooked polenta, until the mixture is creamy. Transfer the processed polenta to a microwave-safe bowl, cover with microwave-safe plastic wrap, and heat on high power until warm.

Day-old pasta often becomes dry and unappetizing, but you can save yourself from mediocre leftovers by planning ahead. Simply save some original pasta cooking water and stir it into the leftovers when you’re reheating them. You’ll end up with leftovers that are almost as moist and tender as the original dish.

Leftover pizza is a treat that can easily be ruined by a spin in the microwave (it gets soggy). Our favorite reheating method for pizza uses the oven. Place the cold slices on a rimmed baking sheet, cover the sheet tightly with aluminum foil, and place it on the lower rack of a cold oven. Then set the oven temperature at 275 degrees and let the pizza warm for 25 to 30 minutes. This approach leaves the interior of the crust soft, the cheese melty, and the bottom hot and crisp but not dehydrated. If you’d rather not heat up the oven for a single slice of pizza, just turn to the stovetop burner. Place the pizza in a cold nonstick skillet, cover it, and turn the burner to low. About 8 minutes in the pan gives the cheese time to melt while the bottom crisps perfectly—no more soggy slices.

Fish is notoriously susceptible to overcooking, so reheating previously cooked fillets is something that makes nearly all cooks balk. But almost everyone has leftover fish from time to time, and the best technique for dealing with it depends on what kind of fish you’ve got. To reheat thicker fish fillets, use a gentle approach: place the fillets on a wire rack set in a rimmed baking sheet, cover them with aluminum foil (to prevent the exterior of the fish from drying out), and heat them in a 275-degree oven until they register 125 to 130 degrees, about 15 minutes for 1-inch-thick fillets (timing varies according to fillet size). For thin fish, it’s very difficult to reheat without drying out and overcooking. Your best bet is to try serving leftover cooked thin fish in cold applications like salads.