Melt the ghee in a large pot over medium heat. Add the celery, onion, and carrots and cook for 4 to 5 minutes, until tender. Add the garlic and cook for 1 minute more. Add the coriander, cumin, salt, pepper, broth, and pumpkin and stir to combine. Bring to a boil, then lower the heat and let the soup simmer for 10 minutes.
Add the shredded chicken to the pot and stir to combine. Heat briefly, just to warm the chicken, then taste for seasoning, adding more salt and pepper if needed.
Ladle the soup into bowls and garnish each serving with avocado slices, cilantro, a squeeze of lime juice, and some coarse salt and cracked pepper.
If you do not have TEX MEX blend, you can use 1 tablespoon of cumin, 1 tablespoon of coriander, 1 teaspoon sea salt, 1 teaspoon black pepper.