Heat the oil in a large stock pot over medium heat.
Add the onion and saute for 3 minutes, or until translucent and fragrant. Add the garilc and peppers, sprinkle with sea salt and pepper and saute for an additional 3-5 minutes until soft and fragrant.
Sprinkle the mixture with the arrowroot or tapioca and stir to coat. Slowly pour in the chicken broth, stirring to combine with the veggie mixture.
Stir in the diced tomatoes, green chiles, cumin and chili powder. Bring to a boil, stirring occasionally. The soup will thicken as it cooks.
Add the chicken, reduce heat to medium-low and let the soup simmer uncovered for 5 minutes, stirring occasionally.
Stir in the lime juice and nutritional yeast (if using), then taste the soup and season with salt as desired. Simmer for 5 more minutes or longer, if desired.
Serve hot garnished with avocado, red onion and cilantro, plus the Whole30 sour cream (optional, see below).
In a small bowl, whisk together the coconut cream with the lemon juice and a pinch of sea salt, to taste. It should taste similar to sour cream.**
