In large skillet over medium heat add turkey, diced onion and minced garlic and cook until turkey is browned.
Add chopped cilantro, salt, pepper, coriander, chopped tomatoes and sour cream. Then add fresh lime juice to taste (start with 1 tablespoon and add more as desired).
Stir and cook for 2-3 minutes until mixture is warmed through. Taste and add salt and pepper, if needed.
Serve immediately in lettuce leaves with additional sour cream, chopped avocado and grated cheese, if desired.