To make the chicken, stir together oil, lime juice, chopped chilies, adobo sauce, garlic powder, and salt in a large bowl. Add chicken and toss to coat. Cover and let sit in the refrigerator for at least 2 hours or up to overnight.
Heat a large pan over medium-high heat. Remove chicken from marinade, and add to pan. Cook, stirring, until cooked through, about 5 minutes. Set aside.
To make the rice, add salt and rice to a pot of boiling water. Return to a boil, then reduce heat, cover, and simmer until water is absorbed and rice is tender, 15-18 minutes. Uncover and fluff with a fork, then toss in lime zest, lime juice, cilantro, and additional salt to taste.
To assemble, arrange rice and lettuce in the bottom of a serving bowl and top with the chicken, diced tomatoes, diced avocados, corn, black beans and red onions.
Make ahead: The chicken and rice can be cooked up to 4 days ahead of time.