Heat a large high sided skillet over medium-high heat with 2 tablespoons vegetable oil. Add the meat and brown, 5 minutes.
While meat browns, grate the zucchini and carrots with a box grater. Add the vegetables to the meat and grate in the onion and garlic. Season the meat with chili, cumin, coriander, salt and pepper and cook 7 to 8 minutes more to soften vegetables. Stir in beef stock.
Grease a 8 by 13-inch baking pan with vegetable oil. Layer in 3 overlapping flour tortillas and top with 1/3 meat, 1/3 cheese. Repeat the layers twice and bake 10 to 12 minutes to brown cheese.
Top with scallions, lettuce and tomatoes, cut into squares and serve.