In a bowl, combine mutton pieces with yogurt, ginger-garlic paste, turmeric powder, red chili powder, and salt. Mix well to coat the mutton evenly.
Cover and refrigerate the marinated mutton for at least 2 hours to allow the flavors to meld together.
Serve hot Mutton Kassa with steamed rice or paratha. Enjoy the rich and spicy flavors of this classic Bengali dish!