The two Miami chefs behind USBS have a special delivery for you: a gourmet burger that will blow your mind.

A pop-up burger restaurant that's been hitting the streets of Miami since October, USBS (United States Burger Service) was inspired by a brainstorming session among friends Dave Bailey, Agustin Gamboa, and Michael Mayta.

"I was in between jobs and did a lot of sitting around and twiddling my thumbs," Mayta says. "My friend Dave and I had ideas for a fast-casual burger where everything was made in-house and reasonably priced. What started as a 15-minute conversation took off from there."

Today, chef team Mayta and his wife, Keily Vasquez, are the magic behind USBS burgers. Born and raised in Miami Beach, Mayta — a graduate of Johnson & Wales University — currently works with Michelle Bernstein on special projects. A pastry chef by day, Vasquez grew up in the restaurant industry in El Salvador, also working with Michelle Bernstein before opening Miami-based Illegal Bakery.

You can find USBS most Saturday evenings at Boxelder in Wynwood. The duo begins serving at 5 p.m., selling anywhere between 80 to 100 burgers before closing up shop for the night. Their signature burgers are the result of countless recipes and over three months' worth of testing everything from the bread and meat to sauces and sear. Priced at $6 to $8, this is easily one of the best burgers for under $10.

Order a single or double patty — appropriately dubbed "ground" or "two-day" — and your burger arrives fresh off the grill in a USBS-branded bag. It's topped with nothing but the chefs' own melted cheese sauce: a blend of two cheeses spiked with a touch of salt and a dash of mustard seed. And it's fitted between two halves of a locally made roll the couple says they developed to be a cross between a Parker roll and potato bread.

Michael Mayta and Keily Vasquez

USBS

According to Mayta, the signature USBS salty hard sear is what sets this sandwich apart from all the rest. The burger is cooked in the rendered fat trimmed from the meats used in USBS' in-house blend. Keeping the burger itself center stage, Mayta will refuse your requests for lettuce, tomato, sauce, or pickles.

But he's doing you a favor: It's so you can appreciate the flavor of the meat and cheese combo. "We needed to have a burger that was good enough to be able to say no to special request toppings and have them still be OK with it. It's nothing fancy. Just an everyday burger that doesn't break the bank."

Don't forget to add "insurance." For an additional $3.50, a serving of thick-cut fries will be handed to you in a white envelope.

While the core menu stays the same, the couple often serves up a one-off specialty burger with creative, quippy names like "A Pair to Brie-Member" or "Blootie and the Blowfish." A recent feature included the "Pho-Lafel," a recipe created in partnership with Nando Chang of Itamae featuring a single beef patty, a falafel patty, pho-style faux pickles, and the duo's "basic bitch" spicy mayo.

"I view the USBS team the same way I view the burger," Mayta says. "The bun is my wife — she's got a tough exterior but she's all soft in the center. The cheese is Dave for his chipper attitude and smiles. And the meat is Agustin for his Argentinean background and knowledge of beef. And the sauce is me — it ties everything together."

USBS Pop-Up at Boxelder. 2817 NW Second Ave., Miami; facebook.com/usbsmiami. Saturdays 5 p.m. until sold out.

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