Drain tofu and blot well with paper towels.

Cut the drained tofu into 1/2-inch dice and set aside.

In a wide skillet, heat olive oil over medium heat.

Add finely chopped onion to the skillet and cook, stirring often, until lightly golden (about 9 minutes).

Gently stir in the diced tofu, torn or cut tortillas, drained diced tomatoes, drained chopped green chilies, ground cumin, and salt.

Add enough of the reserved tomato liquid to moisten the mixture, then blend gently but thoroughly.

Cover the skillet and cook for 10 minutes, allowing the flavors to meld and the tortillas to soften.

If using cheese, sprinkle it evenly over the tofu mixture, then cover and cook until melted (about 2 minutes).

Serve hot, garnished as desired.