Make this grab-and-go Tex-Mex–inspired soup when you have leftover chicken, or use rotisserie chicken for this easy meal-prep soup. The frozen pepper-onion mix adds flavor and saves time in the kitchen, while the black beans add fiber and protein. Combine everything but the broth ahead of time, then add it and heat it in the microwave when you’re ready to eat. If you don’t wish to travel with liquid broth or don’t have access to a microwave, you can use reduced-sodium bouillon instead and just add hot water.