When we sought to transform the economical, tough and often overlooked eye round into a succulent, tender—perhaps even tenderloin-­like—roast, chef Harold Moore told us two ingredients would be key: time and patience.

We added a third: prunes.

Eye round “is definitely overlooked because it’s tricky. It doesn’t really braise well,” said Moore, of Harold’s restaurant in Manhattan’s Soho district.

The cut comes from the animal’s hard-working hindquarters. As such, it lacks the marbled fats of more expensive cuts that melt into the meat, making it juicy and tender. “If you look at it when it’s raw, you can see the fiber of the muscle,” Moore said. “You really need to break that down.”

He accomplishes this by marinating for several days, then cooking it low and slow on a spit before giving it a long rest. We loved the flavorful results, but the lengthy spit-style cooking Moore relies on simply isn’t practical for the home cook.

We knew that traditional marinades only get you so far. Even with salt, which helps them penetrate the meat, they rarely deliver flavor beyond the surface. We needed a marinade that had staying power during roasting. The solution was unexpected: pureed prunes.

That may sound unusual, but prunes are high in fructose, which caramelizes more quickly and at lower temperatures than other sugars. Combined with salt and such umami-packed ingredients as soy sauce, ketchup and anchovies (which melt into the dish without a trace of fishiness), the puree amplifies the meat’s savory notes. We found it also adheres well to the roast, holding in moisture and creating a caramelized crust. Black peppercorns and rosemary provide a familiar holiday flavor backdrop.

The roast beef tasted best after marinating for 48 hours, but 24 hours will work, too. Roasted on a rack at just 275°F (important for even cooking), it took about two hours to become perfectly tender. Thinly sliced and served with a fresh horseradish sauce, the eye round was as toothsome as beef tenderloin, without the expense.