This spicy Mexican dish is piled high with vegetables.
Preheat oven to 400°F. Coat a baking sheet with olive-oil spray.
Place 4 tortillas on a baking sheet and sprinkle with 1/2 teaspoon of cumin. Bake for 8 minutes, until golden. Remove from the oven; transfer to individual plates. Set aside.
Meanwhile, in a large skillet, combine remaining cumin, soy sauce, and liquid smoke. Set pan over medium-high heat and bring the mixture to a simmer. Add vegetable mix and cook for 3 minutes, until tender. Using tongs or a slotted spoon, remove the vegetables from pan; set aside.
To the same pan, add roast beef and simmer for 2 minutes, until hot.
Top toasted tortillas with lettuce, then pepper stir-fry mixture and roast beef. Arrange avocado on top. Serve with additional tortillas on the side. (Additional garnish options: fat-free sour cream, salsa, jalapeños, hot sauce.)