Mix minced meat with grated onion, pressed garlic, beaten egg, parboiled rice, meat seasoning, salt, and pepper in a deep container. Form into meatballs.
Coat a baking dish with butter, reserving the rest for sauce. Add meatballs. For earthenware or porcelain dishes, start in a cold oven; otherwise preheat to 200°C (392°F). Bake for 15-20 minutes.
In a frying pan, melt the remaining butter over medium heat. Add flour and stir for 1-2 minutes. Pour in broth or water and sour cream, stirring gently. Add meat seasoning and cook for about 1 minute until sauce thickens.
Pour the sour cream sauce over the baked meatballs and return to oven. Bake at 200°C (392°F) for 20-25 minutes, spooning sauce over meatballs every few minutes. Remove and let rest for a few minutes.
Sprinkle with fresh herbs and serve in the baking dish.