Heat 1 tablespoon of olive oil in a large nonstick skillet over medium heat. Add onions, jalapeno, and garlic. Cook for 3 minutes, stirring occasionally, until onions begin to soften.
Add corn, black beans, tomatoes, oregano, cumin, and a pinch of salt. Cook for 3 more minutes, stirring occasionally.
Transfer filling to a medium bowl, cover, and set aside. Wipe down the skillet with a paper towel to clean.
Heat the remaining 1/2 tablespoon of olive oil in the over medium heat. Pour in the whisked eggs, season with a pinch of salt, and cook for 2-3 minutes until the eggs have just set. Remove from heat.
Add the shredded cheese and the corn and bean filling mixture to the middle of the cooked eggs.
Carefully fold the omelet over on both sides using a spatula, transfer it to a plate, and top with sour cream, chunky salsa, avocado, and cilantro. Serve immediately.
Notes
Want it extra spicy? Use serrano peppers instead of jalapenos.
Don’t have Mexican oregano? You can use regular oregano insead. I highly recommend you try to buy some Mexican oregano for next time as it has a different flavor than the typical oregano you can find in most stores!
Don’t have shredded Mexican-blend cheese? You can use Monterey Jack, cheddar, or mozzarella.