Adjust rack to middle position and preheat oven to 425 degrees. Wash and dry produce.

Trim and thinly slice scallions, separating whites from greens. Quarter lime.

Heat a drizzle of oil in a large, heavy-bottomed pot over medium-high heat. Add beef*, scallion whites, a pinch of salt, and pepper. Cook, breaking up meat into pieces, until browned and cooked through, 6-8 minutes. TIP: If you don’t have a pot that’s big enough, use a large pan and work in batches.

Once beef is cooked, carefully drain any excess grease from pot, if necessary. TIP: Use a slotted spoon to transfer beef to a bowl, then pour out grease and return beef to pot.

Meanwhile, drain beans. Halve tortillas.

To pot with beef, stir in beans, crushed tomatoes, Tex-Mex paste, and stock concentrates. Cook, stirring constantly, until well combined, 1-2 minutes.

Taste and season with salt and pepper if desired.

Arrange four tortilla halves, cut sides facing out, on the bottom of a lightly oiled 8-by-8-inch baking dish (use eight tortilla halves and a 9-by-13-inch baking dish for 8 servings).

Spread one-third of beef mixture in an even layer over tortillas, then top with one packet of cheese (two packets for 8). Repeat two more times with remaining tortillas, remaining beef mixture, and remaining cheese.

Lightly coat a large piece of aluminum foil with nonstick cooking spray. Cover baking dish tightly with foil, coated side down. Place baking dish on a baking sheet.

Bake “lasagna” on middle rack until cheese melts and filling is hot and bubbling, 10-12 minutes (be careful when lifting the foil to check doneness—hot steam may escape!). TIP: For a browned crust, broil, uncovered, for an additional 2 minutes after baking.

Crush tortilla chips in bag.

Once “lasagna” is finished baking, let cool at least 5 minutes before serving. Sprinkle “lasagna” with scallion greens. Serve family style with sour cream, tortilla chips, lime wedges, and hot sauce on the side.