Those loins are not getting any younger.

In fact, the 40 wagyu loins sitting in a subterranean walk-in at the Shaw Bijou construction site will likely dehydrate into leather medicine balls before chef Kwame Onwuachi can open his highly anticipated fine-dining restaurant later this year. So the former "Top Chef" contestant has decided to use the 100-day dry-aged meat to create what sounds like the Cheesesteak of the Gods for an outdoor pop-up at Union Market from April 1 to 3.

The Cheesesteak of the Gods will begin with Onwuachi's 100-day dry-aged wagyu beef. (Photo by Kwame Onwuachi)

"I've had this fast-casual concept that I've been working on called Philly Wing Fry," says Onwuachi during a phone interview. "I figured I have all this meat now. I might as well get rid of it and then donate the proceeds."

[Ready or not, here comes chef Kwame Onwuachi and his fine-dining concept.]

So, yeah, the $15 for your mini-cheesesteak, tamarind-glazed wings, waffle fries and a house-made soda will go straight to No Kid Hungry. But that's not what you really care about, right?

For the vast majority of Washingtonians — those who didn't shell out for the multi-course meals that Onwuachi prepared during the nomadic Dinner Lab events in the D.C. area — this popup will provide their first taste of the chef's cooking. Not that this fast-casual fare will measure up to the food expected at Onwuachi's eight-table Shaw Bijou, now scheduled to open in late May in Shaw.

"The attention to detail would probably be similar, but everything else? The food? Not so much," says Onwuachi.

Onwuachi's cheesesteak, like none you'll find in Philly. (Photo by Kevin Carroll)

The pop-up meal starts with the chef's take on a cheesesteak, which will surely bring out the D-cell batteries once Philly natives hear about the preparation. Onwuachi will slice and griddle a four-ounce portion of dry-aged wagyu (sourced from Japan Premium Beef) before slipping it into a miniature banh mi roll from Lyon Bakery. The meat will be topped with smoked provolone, roasted garlic aioli, pickled pearl onions and caramelized onions. Oh, one other thing: The mini roll will be toasted with dry-aged beef fat, rendered from scraps carved off the loins.

Onwuachi will pair that cheesesteak with hand-cut waffle fries and a pair of chicken wings (each including a wing and drumette), which will be confited for six hours, then cooled and fried to order. The wings will be coated with a spicy tamarind glaze prepared with shallots, garlic, chili peppers, fish sauce, coconut palm sugar and tamarind puree.

The dish is basically the chef's version of double-fried Korean fried chicken.

You can wash down this chef-driven bar food with one of three house-made drinks: a strawberry-rhubarb soda, cucumber-apple soda or yuzu-black tea-sea buckthorn lemonade.

So how did Onwuachi land on the random dishes that define his Philly Wing Fry concept?

"Philly cheesesteaks, chicken wings and waffles fries. I love those three things," he explains. "Why wouldn't I want to eat them together?"

Onwuachi has one more surprise for those who arrive to his three-day popup on the patio at Union Market: "I'll be serving chicken and waffles for people waiting in line."

Yep, he'll be using the same mini-frozen waffles that got Onwuachi booted from "Top Chef."

Onwuachi calls it his "little joke." It's also a little reminder that this fine-dining chef knows how to laugh at his own imperfections.

The Philly Wing Fry outdoor pop-up opens at 11 a.m. April 1 and runs through April 3 at Union Market, 1309 Fifth St. NE. The $15 meal includes a miniature cheesesteak, tamarind-glazed wings, waffle fries and a house-made soda.