Prepare leeks and mushrooms. Combine with turkey, bread crumbs, and yogurt in large bowl until well blended. Add rosemary, garlic powder and cheese. Form into ~30 meatballs
In separate bowl, mix tomato soup, sour cream, other 1/2 cup yogurt and oregano until pale orange for sauce. Add salt and pepper to taste.
Heat frying pan to medium, and sautee meatballs in olive oil. Cook for ~10 minutes or until lightly browned, rotating and flipping frequently. Drain of excess moisture.
Add sauce mixture to pan and coat meatballs. Bring mixture to slight boil until meatballs are cooked through. Serve on rice.