1Add chicken to a bowl with marinade ingredients. Mix, cover, and refrigerate for at least 20 minutes.
2Wash rice until water runs clear; drain. Transfer to a pot, add water and salt. Bring to a boil, then simmer for 15 minutes. Let rest, covered, for 10 minutes. Stir in cilantro, lime, and butter.
3In a small pot, combine black beans, cumin, chili powder, and salt. Cook until warmed through (about 5 minutes).
4Preheat a large pan over medium-high heat. Add olive oil and sear chicken for 5-6 minutes per side (10-12 minutes total) until internal temp reaches 165F. Let rest 5 minutes, then cut into small cubes.
5Build bowls with rice, beans, romaine, and chicken. Top with desired toppings (guacamole, salsa, cheese, sour cream).