2 tablespoons extra-virgin olive oil
1 large onion, chopped
1 1/2 cups fresh corn kernels (see Tip) or frozen, thawed
4 large tomatoes
1 1/2 cups cooked long-grain brown rice (see Tip)
1 15-ounce can black, kidney or pinto beans, rinsed
1 tablespoon chili powder
1 1/2 teaspoons dried oregano, divided
1/4 teaspoon salt
1/2 cup chopped fresh cilantro
1/3 cup prepared salsa
2 cups shredded iceberg or romaine lettuce
1 cup shredded pepper Jack cheese
2 1/2 cups coarsely crumbled tortilla chips
Lime wedges for garnish