Place the rice in a medium saucepan and cover with 1 cup of water. Bring the rice and water to a boil over high heat. Stir and reduce the heat to low, cover and cook for about 35-45 minutes or until all water has been absorbed. Uncover, cool slightly and set aside.
Pour the olive oil in a large non-stick skillet and place over medium heat. Add the chopped onion and corn kernels and cook, stirring occasionally, for about 5 minutes.
Add the shredded cabbage and sauté for a few minutes or until the cabbage starts to wilt. Coarsely chop 1 tomato and add it to the corn mixture along with the black beans, cooked rice, chili powder, Sriracha seasoning, 1 tablespoon water, 1 teaspoon oregano and salt. Cook, stirring occasionally, for 5 minutes or until the tomatoes start to break down. Add another tablespoon of water if the mixture seems dry. Remove from the heat and cool slightly.
Chop the last 3 tomatoes and place in a medium bowl. Add the cilantro, prepared salsa, and ½ teaspoon oregano.
In a large bowl toss the lettuce with the bean mixture together until combined. Add half the salsa and half the grated cheese.
Serve topped with crumbled tortilla chips, diced avocado, and shredded cheese. Garnish with lime wedges and pass around the remaining salsa.