Combine the chicken, taco seasoning, and 1 tablespoon vegetable oil in a large bowl or sealed bag; marinate in the refrigerator for 20 minutes or up to 48 hours.
Heat a large skillet over medium-high heat. Cook the chicken 5–7 minutes per side, until an internal temperature of 165°F (74°C) is reached. Transfer to a cutting board and rest 10 minutes, then chop into bite-size pieces.
In the same skillet, add 1 teaspoon oil and sauté the sliced bell peppers and 1/2 onion (sliced) for 3–4 minutes, until tender; set aside.
Meanwhile, bring 2 cups water to a boil in a large pot. Add 1 cup basmati rice, 1 teaspoon oil, and salt and pepper to taste. Cover, reduce to low, and cook until the rice is tender and water is absorbed. Remove from heat, stir in 2 tablespoons chopped cilantro, and fluff with a fork.
Make the guacamole: mash the avocado in a small bowl and stir in half the minced cilantro (1 tablespoon), half the minced onion (about 1 tablespoon), half the minced jalapeño, juice of 1/2 lime, and salt and pepper to taste; set aside.
Make the tomato salsa: combine the diced tomato with the remaining minced cilantro (1 tablespoon), remaining minced onion (about 1 tablespoon), and the remaining minced jalapeño; season with salt, pepper, and a squeeze of lime if desired.
Assemble the bowls: divide the rice, chicken, sautéed peppers and onions, and black beans evenly into 4 meal-prep bowls. Divide the chopped romaine, tomato salsa, guacamole, and sour cream into the remaining 2 containers for fresh-serving bowls.
When ready to eat, reheat only the containers with chicken and rice in the microwave for 2–3 minutes, then top with the fresh salad, salsa, guacamole, and sour cream from the cold containers.