Vegetarian Taco Salad

Name: Vegetarian Taco Salad
Ingredients: 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 ½ teaspoons dried oregano, divided; ¼ teaspoon salt; ½ cup chopped fresh cilantro; ⅓ cup prepared salsa; 2 cups shredded iceberg or romaine lettuce; 1 cup shredded pepper Jack cheese; 2 ½ cups coarsely crumbled tortilla chips; Lime wedges for garnish