Combine the salsa, garlic and cumin in a large saucepan. Add the chicken. Cover and bring to a boil over medium heat. Reduce the heat to low and simmer for 12 to 15 minutes or until the chicken is no longer pink in the center, stirring occasionally. Remove the chicken to a plate and shred with a fork. Return the chicken to the saucepan, stir in 1/4 cup of the sour cream. Heat on low until warm. Combine the remaining sour cream, lime juice, and salt in a small bowl. Spoon the chicken mixture into the tortillas. Top with the lettuce, avocado and drizzle with lime crema.