Preheat the oven to 375ºF.
In a large bowl, combine the lamb mince, onions, spices, salt, one egg and peas. Mix well until evenly combined.
Crack the egg into a small bowl and beat lightly. Set aside.
Unroll the puff pastry. Spoon the keema mixture along one long edge of the pastry, forming a neat sausage shape. Brush the exposed edge with egg wash, fold over the filling and roll tightly to seal.
Brush the top of the roll with egg wash and sprinkle with cumin seeds and black mustard seeds (or nigella and sesame seeds if using).
Cut the roll into even pieces and place on a lined baking tray, spacing them slightly apart.
Bake for 25–30 minutes, or until golden brown, crisp and cooked through. Serve hot or at room temperature.
