Heat avocado oil in a large skillet over medium-high heat until shimmering.
Add diced chicken breast and cook 3–4 minutes without stirring to develop color.
Sprinkle taco seasoning over the chicken, stir to coat, then add water or chicken broth.
Cook until chicken reaches 165°F and most liquid has evaporated, about 8–10 minutes total.
While chicken cooks, prepare brown rice according to package directions or make cilantro lime rice in an Instant Pot.
In a separate skillet, heat drained black beans and frozen corn over medium heat until warmed through, about 5 minutes.
Spread cooked components on sheet pans and cool to room temperature for food safety and best texture.
Divide chicken, rice, bean–corn mixture, and shredded cheese evenly among 8 airtight meal prep containers.
Add a spoonful of salsa to each container, or keep it separate if preferred. Store tortillas separately.
Label each container with the prep date and refrigerate. Add fresh toppings (guacamole, sour cream, pico) at serving time.