Step 1

Stir reserved beef birria sauce, chicken broth, carrots, celery, and cabbage together in a saucepan over high heat; bring to a simmer. Reduce heat to medium-low and simmer, occasionally brushing the caramelized bits (side fond) off the side with the hot liquid, until vegetables are nice and tender and consomé has reached desired consistency, about 20 minutes. Reduce heat to low and keep hot while you prepare the tacos.

Step 2

Heat some reserved beef fat in a large skillet over medium heat until melted. Add 2 tortillas and toss with a spatula until generously coated in fat. Toast briefly until golden brown, then cover with Monterey Jack cheese and some shredded beef. Drizzle each taco with about 1 tablespoon consomé liquid, then top with white onion and cilantro.

Step 3

Fold tacos in half and press gently. Continue to cook, flipping back and forth, until browned and crispy, 2 to 3 minutes. Transfer to a plate and repeat to make remaining tacos, adding more fat if necessary.

Step 4

Ladle consomé into a bowl and garnish with remaining white onions and cilantro. Squeeze lime wedges into consomé and serve with tacos.