Heat olive oil in a large skillet (cast iron works best). Add onion, bell pepper, zucchini, mushrooms, garlic, and jalapeo, and saut for about 10 minutes, until just tender. Add lemon juice, cumin, chili powder, and stir well. Sprinkle with chopped cilantro.
To serve: Fill tortilla shells with beans and vegetable mixture, and garnish with guacamole and salsa.
Nutritional information per serving: 385 calories, 14 g protein, 11 g fat, 0 g saturated fat, 63 g carbohydrate, 14 g fiber, 6 g sugar, 235 mg sodium.