1 cup of roughly chopped zucchini or summer squash (1-2 zucchini or squash, depending on the size)
1/2 medium onion, chopped
1 garlic clove, chopped
1 large fresh mild green chile (Anaheim or Hatch), seeds and stem discarded, chopped
1/2 fresh jalapeño chile pepper, seeds and stem discarded, minced (or more, if you desire more heat)
Pinch of ground cumin
Pinch of ground oregano
1 small to medium tomato, chopped
4 corn tortillas
4 slices cheddar cheese
1/4 cup crumbled Mexican cotija cheese (a salty, crumbly cheese, you can substitute feta)
A few sprigs of fresh cilantro, chopped (okay to include the stems, if small)
1 Heat a tablespoon or two of oil in a large sauté pan on medium high heat. Add the zucchini, onions, garlic, green chiles, and jalapeño to the pan. Sprinkle with salt and cumin. Stir to coat the vegetables with the oil in the pan. Spread the veggies out in the pan and then stir only occasionally, until they are all lightly browned. Stir in the chopped tomatoes and oregano, lower the heat to low. Let gently cook for several minutes while you are preparing the tortillas.
2 You are going to want to heat up the tortillas first, first to soften them, and then to melt the cheese. There are two basic ways of doing this. One way is on the stove top, preferably in a cast iron pan. Another way is to use the microwave. In both methods you will work in batches. (A third way is to use fresh homemade corn tortillas, which is a great option if you are set up for it.)
2a Preparing tortillas on the stove-top Heat a dollop of olive oil (or other vegetable oil) in a large cast iron frying pan, on medium high. Add a tortilla to the pan, moving it around a bit, and turning it over, so that it spreads around the oil. Let the tortilla heat until it develops little bubbles of air pockets. Then place a piece of cheese on one side of the tortilla, and use a metal spatula to fold the other side of the tortilla over the cheese. Heat until cheese is melted, then remove from pan. Note that if you have a big enough pan, you can have one tortilla folded over while you have another tortilla doing its initial heating.
2b Preparing tortillas in the microwave Place a paper towel (or half a paper towel) on the heating surface of your microwave. Spread out 2 tortillas on the paper towels. Cook on high heat for 20 seconds per tortilla, in the case of 2 tortillas, 40 seconds. The tortillas should develop air pockets. (Note that every microwave is a little different, and corn tortillas differ as well. So you may need to adjust the times for your particular setup.) Then place a slice of cheese on one side of each tortilla and fold the tortillas over the cheese. Cook for an additional 10 seconds per tortilla (20 seconds for 2 tortillas), or until the cheese is melted.
3 Open the tacos and spoon some of the cooked veggie filling into them. Sprinkle on chopped cilantro and crumbled cotija cheese. Serve immediately.