Heat a large pot over medium-high heat, add oil, the onions and ground turkey. Saute until turkey is just cooked; stirring frequently to break up clumps.
Add the chicken stock to the pan and stir in garlic, chiles, tomato puree and enchilada sauce mix. Bring to a boil then reduce heat and simmer for 10 minutes. Put some of the chopped avocado in the bottom of each bowl and ladle the soup on top; stir to combine. Top with cheese, crushed chips and sour cream. Garnish with cilantro.