Forget elaborate prose descriptions. A word or two will suffice: scallops, prawns, rabbit, crab, salad, chicken wings. The restaurant, squeezed into a guava-pink bungalow, is modeled on a “fonda,” a modest establishment where a grandmother may stir up a beef stew for the surrounding neighborhood.

With that mission in mind, Mr. Enrique’s early message to Puerto Rican farmers was blunt: “ ‘You come to me, I’ll buy everything on your truck,’ ” he said. “ ‘You tell me that’s from your land and you picked it this morning? I’m buying it.’ And that kept getting bigger and bigger and bigger.”

Maybe the source is the 20-something hipster “with boatloads of purslane,” he said, or the fisherman who calls and tells the chef that he just caught a conger eel. “My favorite are the local oysters,” Mr. Enrique said. “They’re so fresh it’s ridiculous. That’s something I’m trying to work with now.” The oysters adhere to the roots of partly submerged mangrove trees.

A road trip with Mr. Enrique can turn into an ad hoc lesson in marine biology, or horticulture. While dropping into a lechonera in the hills above San Juan for a rustic Saturday breakfast of roast pork and blood sausage, the chef ambled over to the foliage near the barbecue pit and pointed to a tangle of flora. “You see that thick leaf with the little flowers?” he said. “That look like zucchini blossoms? That’s calabaza.” Calabaza is a popular squash, but the blossoms are usually tossed away.

“That’s a vine, it just grows like crazy,” he said. Like more and more chefs in Puerto Rico, Mr. Enrique’s impulse is to find a way to use it. “The ingredients are what drive me,” he said. “It’s not about what you can do with an ingredient. It’s what you don’t do to it. So to make that happen, you need to find what’s best.”

Out on Vieques, the still-wild island that for decades has been known for bewitching peace seekers, lost souls and the United States military (which used part of it for years as a naval training range), that quest for indigenous bumper crops takes on a more haphazard form. Islanders just show up at the kitchen pass with goodies (star fruit, mango, papaya) that they plucked on a stroll into town. “We have urban foragers,” Mr. Enrique said.