Preheat large non-stick skillet on medium-high heat and swirl 1 tbsp oil to coat.
Add onion and saute for 1 minute, stirring occasionally.
Add ground meat, taco seasoning, and salt. Saute for 7 minutes, constantly stirring and breaking into small pieces with spatula.
Add diced green chiles, diced tomatoes, black beans; stir and bring to a boil. Cover and simmer on low for 5 minutes.
Lay tortillas overlapping each abit, sprinkle with cheese, turn off the heat, cover with a tight lid, and let stand for 5-10 minutes.
Sprinkle with lettuce, diced tomatoes and whatever else Mexican topping you like.
Serve hot with desired toppings like cilantro, green onion, avocado, yogurt, salsa etc.