Leftover oven-braised chicken sauce provides a colorful and flavorful contrast to wild mushroom risotto. (Edward Schneider for The Washington Post)

I’m talking not about obviously useful things like a single slice of roast beef, enough for a sandwich, but about peripheral scraps: a quarter-cup of sauce, say, or a half-cup of rice.

On the latter, I’ve written about turning a little leftover paella into savory pancakes, and I recently cooked a nice three-egg frittata using perhaps 3/4 cup of leftover rice pilaf, diced red bell pepper and herbs. With tomato sauce, it made a pleasing dinner for two and was elegant enough that we could have served it to company as a first course.

At my wife, Jackie’s, urging, I’ve taken to saving small quantities of sauce. Some I freeze in little plastic-wrapped spheres; these I tend to forget about (they’re so small!). Others remain in the fridge for a few days, hoping they’ll be repurposed.

Sauces or gravies generated as part of braising or stewing or simmering meat and vegetables have lots of flavor. Sometimes they can be reused as is or with the addition of fresh herbs or an acidic element such as chopped cornichons. Sauces or gravies can be used to enrich other sauces as well, so long as the old dish and the new are not dissonant. (Sure, some classic recipes use meat-based sauces with seafood and vice versa, but you may prefer not to randomly use gravy from a pot of braised lamb shanks in the sauce for a delicate piece of steamed halibut. It could work with clever manipulation, but chances are it wouldn’t.)

I recently remembered another use for a wee bit of delicious sauce — to add a contrasting element to a homogeneous dish: risotto in this case. We love risotto and generally eat it at least once a month. In Italy and in restaurants worldwide, risottos are traditionally served as first courses, but when we’re home alone, we rarely eat more than one dish per dinner. So our risotto portions are a bit larger and constitute the whole meal. Even when there are chunky ingredients in a risotto — winter squash, say, or shrimp — the dish offers only one flavor, albeit a delicious one.

A few days before, we’d had chicken, an oven-baked braise with finely slivered leeks, red bell peppers, rosemary, chicken stock and halved lemons (which I had previously salted and sugared overnight). The sweet-tart-bitter sauce, with all those ingredients, was rich with chicken and other flavors and almost syrupy after its time in the oven. There was 1/3 cup left, and I wisely didn’t throw it away.

When I made our risotto with wild oyster mushrooms (after years of not bothering with the bland cultivated ones, I’d forgotten how good these are when gathered in the woods), I thought of those few spoonfuls of sauce. I reheated the sauce (like a leek-and-pepper compote of great intensity), checked it for seasoning and dribbled some onto each portion of risotto.

First of all, it looked great, with those glistening filaments of leek coated in rich brown sauce. More important, though, it mated well with the main ingredients: Chicken and vegetables are a natural with rice and mushrooms, after all. And the sauce did its job: It provided contrast, enabling us to vary our forkfuls of risotto in a flavorful and interesting way.

So the answer to that first question is: Throw nothing away, within reason, so long as it has good flavor.

Schneider’s Cooking Off the Cuff appears Fridays in All We Can Eat. Follow him on Twitter @TimeToCook

Further reading:

* Cooking Off the Cuff: Secondhand rice is nice