Lamb biryani rolls

Name: Lamb biryani rolls
Prep time: 15 min
Cook time: 25 min
Total time: 40 min
Cuisine: Indian
Ingredients: 1/2 cup (100g) basmati rice (to give about 1 1/2 cups cooked rice); 2 eggs; 400g lamb mince; 1 teaspoon garam masala (Indian spice mix); 1/2 teaspoon ground turmeric; Pinch of ground cardamom; 1/2 onion, finely chopped; 2 teaspoons finely grated ginger; 3 sheets frozen puff pastry, thawed, halved; 2 teaspoons nigella seeds (optional); Mango chutney & salad leaves, to serve