Prep ingredients: trim green onions and separate whites from greens; mince the white parts and chop the green parts so you have 1 1/4 cups chopped green onions total. Seed and mince the 2 jalapeños. Mince 3 cloves garlic. Seed and dice 2 Roma tomatoes. Chop 1/3 cup cilantro. Peel, core and dice 3 medium avocados and set aside. If using rotisserie chicken, shred 3 cups now; if using raw chicken breasts, leave them whole for cooking.

In a large pot, heat 1 Tbsp olive oil over medium heat until shimmering. Add all of the chopped green onions (whites and greens) and the minced jalapeños and sauté until tender, about 2 minutes. Add the minced garlic during the last 30 seconds of sautéing and stir.

Add the 4 (14.5 oz) cans low-sodium chicken broth, the diced tomatoes, and 1/2 tsp ground cumin to the pot. Season with salt and freshly ground black pepper to taste.

If using the boneless skinless chicken breasts, add them to the pot now. Bring the mixture to a boil over medium-high heat. If using shredded rotisserie chicken instead, do not add it now; just bring the soup to a boil and proceed to step 5.

Reduce heat to medium, cover, and cook until the chicken breasts are cooked through, about 10–15 minutes depending on thickness (or until internal temperature reaches 165°F). If you used rotisserie chicken, simmer the soup, covered, about 10–15 minutes to meld flavors.

If you cooked chicken breasts: reduce heat to low, transfer the breasts to a cutting board and let rest 5 minutes. Shred the chicken with two forks (or chop) and return the shredded chicken to the pot.

Stir in 1/3 cup chopped cilantro and 3 Tbsp fresh lime juice. If using shredded rotisserie chicken, add it now and heat just until warmed through.

Add the diced avocados to the soup immediately before serving. (If you will not serve the soup right away, add avocado to individual bowls when serving to avoid browning; about 1/2 an avocado per bowl is a guideline.)

Taste and adjust seasoning with salt and pepper if needed. Serve with tortilla chips, monterrey jack cheese, and sour cream, if desired.