Carlos Alvarado approaches my table and asks if I’d like to try the weekend special, a big workingman’s bowl of sopa de pata. The soup, the manager and co-owner says, requires two days to prepare, which perhaps explains why the dish is available only on Sundays, the day of rest for everyone except the cooks at Comedor y Pupuseria San Alejo, an extraordinary Salvadoran restaurant tucked into an ordinary strip center in suburban Maryland.

The steaming bowl placed in front of me boasts an imposing stack of vegetables and garnishes, each cut and arranged to the kitchen’s specifications. There’s corn on the cob, sawed off like tree trunks and submerged in the swampy soup. Chayote squash sliced into long, overturned canoes, onto which ringlets of jalapeño cling to life. Squiggly lengths of cabbage and carrot molded into a wobbly crown of pickled curtido. Chopped herbs tossed willy-nilly across the surface of the soup, like an explosion of confetti, nature’s party popper.

The dark broth that encircles this castle of vegetables contains mysteries of its own: Morsels of long-simmered cow’s feet, as soft and warm as bone marrow. Pieces of honeycomb tripe, its texture serving as a gnarly foil to the silky collagen of the cow trotters. I taste tomato, cumin, lime, even the faintest whisper of heat. This vegetable and offal soup, you quickly realize, offers ample evidence of the brilliance of Salvadoran cooking, a largely subsistence-level cuisine in which cooks have learned to extract every last drop of flavor from the kinds of off-cuts routinely snubbed in this land of plenty.

Salvadorans, I should note, are the region’s largest immigrant group , by a significant margin, and yet after nearly 15 years as a food writer in Washington, this is the first time I recall slurping sopa de pata. I’m not the least bit surprised that it took place in Alvarado’s restaurant. Alvarado is the brother of Mirna Alvarado-Montero, co-owner of Taqueria Habanero, the first name in Mexican cooking in the District and College Park. The siblings are co-owners of San Alejo, named for the small Salvadoran town where they were raised in a family that sold tortillas, empanadas, yuca de chicharron and other homemade delicacies to help make ends meet.

For years, the lines between Mexican, Tex-Mex and Salvadoran cooking have been hopelessly blurred in Washington, the result of Salvadorans fleeing the strife in their home country and opening restaurants here in the 1980s and beyond. Their goal wasn’t necessarily to sow deception, but just to make a living by enticing Washington diners more familiar with tacos, nachos, combo plates, guacamole and the like. But more than 30 years since those refugees first arrived, Washington still has countless restaurants in which pupusas share the same menu with enchiladas and fajitas.

Brother and sister have been working to untangle the ancestries of these cuisines, which admittedly share some DNA. Alvarado-Montero and her husband, Dio Montero, a native of Puebla, Mexico, started the reclamation project with their first Taqueria Habanero on 14th Street NW. Their motto: “99% Mexican.” If you ask a server, “Why only 99 percent?”, she will likely give you a deadeye stare and respond, “Because we’re located in Washington.”

At San Alejo, where he flits between the dining room and kitchen dressed in an apron over his checkered shirt and khaki pants, Alvarado is doing much the same for Salvadoran cuisine. He’s uniquely qualified for the job. After arriving in the United States in 1999, first thinking he might become a doctor, Alvarado eventually found work at José Andrés’s ThinkFoodGroup. He spent a decade with ThinkFoodGroup, including Cafe Atlantico and the Jaleo in Penn Quarter, mastering almost every position in the back of the house, from dishwasher to prep cook to pastry assistant. He considers Katsuya Fukushima, the former chef at Cafe Atlantico and now a partner in the Daikaya Group , to be one of his mentors.

San Alejo was his attempt to “re-create the Salvadoran eatery in Maryland,” Alvarado says. He wanted to serve the “the food [we] used to eat as children.”

The menu has a whole section devoted to pupusas, the stuffed masa cakes that are handmade in the open kitchen and browned on a hot griddle. Their shells are appropriately thin, frequently leading to ruptures in which the three-cheese blend oozes onto the flat-top and solidifies into these irresistibly crispy-and-chewy nuggets. The pupusa fillings borrow from tradition (beans and cheese, loroco and cheese) and push the tradition forward (shrimp and cheese; spinach, mushroom and cheese). Either way, your pupusa will be plated with the kind of cheffy flair usually reserved for restaurants in Shaw or Penn Quarter.

The Salvadoran influences may not be immediately apparent, or well understood, without a deep background conversation with Alvarado. I would come to learn that San Alejo’s tamales de pollo are prepared with chicken stock, oil and a lot of painstaking labor, resulting in a dish that’s more corn mousse than masa log. Papas locas looks like something you might order after a late night on U Street, but the appetizer is a beloved Salvadoran street snack: a pile of thick-cut fries that somehow maintain their crunch despite being splattered with ketchup, mustard, mayonnaise and an aged Salvadoran cheese — a clown’s face of condiments.

The entrees are pure, bone-deep comforts, starting with the parillada San Alejo, a sizzling fajitas-style platter of grilled meats, shrimp and a mild, finely ground Salvadoran-style chorizo sausage. I wish I could tell you the secret to the marinade, but whatever the kitchen uses to tenderize and flavor its beef loin and skirt steak, it leads to the finest versions of lomo saltado and carne asada that I’ve sampled in recent memory. Even the salmon fillet, grilled well past the pink, moist center that I prefer, was saved by the accompanying aioli, this piquant and smoky zigzag of sauce.

San Alejo, like many Salvadoran restaurants before it, does wander beyond its own borders. You’ll find Mexican-style enchiladas (with thicker, Salvadoran-style corn tortillas and a razor-sharp salsa verde mellowed somewhat with roasted garlic) and even Honduran baleadas, this half-moon crepe in which a toothsome housemade flour tortilla is packed with steak (or chicken), refried beans, eggs, avocado, cotija cheese and a sweet drizzle of sour crema. The baleada is every bit as good as the one at El Catrachito in Silver Spring.

Alvarado’s touch with dishes beyond the Salvadoran table reminds me of his original desire to become a doctor, a profession famous for first doing no harm. He now carries a stirring spoon, not a stethoscope, but he clearly understands that this oath applies as much to food as to medical care: He makes sure that no dish suffers under his care — and that everything he touches tastes better in the end.

If you go

Comedor y Pupuseria San Alejo

1819 East-West Highway, Hyattsville , Md., 240-714-3342,

Hours: 9 a.m. to 9:30 p.m. Monday through Thursday; 9 a.m. to 10 p.m. Friday through Sunday.

Prices: $7.50 to $15 for tacos, burritos, quesadillas and entrees; $1.75 to $6 for pupusas, nachos and appetizers.