1 28-ounce can diced tomatoes, drained
2 red bell peppers, sliced 1/2 inch thick
1 onion, cut into 8 wedges
2 teaspoons dried oregano
1 teaspoon ground cumin
kosher salt and black pepper
1 1/2 pounds flank steak, cut crosswise into thirds
1 cup long-grain white rice
1 avocado, sliced
1/4 cup fresh cilantro leaves