Prepare 2kg lamb shoulders, cut into big chunks.
Simmer the lamb with 3 inches of ginger, 2 cinnamon sticks, and 2 bay leaves. If using a pressure cooker, cook for 8 minutes; otherwise, simmer until tender.
For the masala paste, blend 4 large tomatoes, 3 pieces of turmeric root, 4 large green chili peppers, 3 large red chili peppers, 7-8 small chili flakes, 1 red onion, 5 cloves of garlic, and 3 inches of ginger.
In a pan, heat 2 tablespoons of vegetable oil. Add 4 cardamom pods, 4 pandan leaves, finely chopped onions, garlic, and ginger. Sauté until fragrant.
Add the masala paste and sauté for a minute or two until it breaks down. Then add the blended mixture and cook for another few minutes.
Mix in 3 tablespoons of tomato puree and 2 tablespoons of chili powder. Cook for a couple of minutes to combine.
Add 1/2 cup of yogurt, 2 tamarind pieces, and 3 tablespoons of biryani spices. Cook until the tamarind breaks down into a paste.
Add 3 tablespoons of lemon juice, salt, and seasoning to taste. Mix well.
Add the cooked lamb chunks and mix thoroughly with the gravy. Allow it to simmer for a few minutes.
Top with pounded cumin seeds and fried onions before serving over biryani rice.