Preheat the oven to 4000 F (2040 C).
Place chicken breasts in a baking dish. Drizzle with half of the oil and season with chili powder, paprika, garlic, and salt. Rub the seasoning and the oil all over the chicken.
Bake at 400 degrees for about 25-30 minutes.
Meanwhile, add the onion and tomatoes to a bowl with the lemon or lime juice, cilantro, and the remaining oil. Stir to combine.
Divide the peppers, tomatoes, and dressing between jars and add the cooled chicken and lettuce. Place the lid on the jars and store it in the refrigerator.
To serve, dump the contents of the jar into a bowl. Enjoy!
Remove the chicken from the oven and let it rest for 15 minutes. Cut the rested chicken into 1/2-inch cubes.