1Season the mutton with 1 tsp salt. Heat the oil in a pressure cooker on high heat and brown the mutton in 2 batches, about 4 minutes each.
2Lower to medium heat. Add the onion, carrot and celery and cook 8 minutes. Stir in the ginger garlic paste for 1 minute.
3In a small pan on low heat, dry roast the coconut and sesame for 2 to 3 minutes. Grind with the Kolhapuri masala and 1/4 cup water to a smooth paste.
4Fry the paste in the cooker on medium heat for 2 minutes. Add tomato puree, water, bay leaves and the mutton. Close, cook on high to the first whistle, then on low 25 minutes. Let the pressure release naturally.
5Lift out the mutton, pull it off the bones with two forks and discard the bones and bay leaves. Return the meat and simmer uncovered on medium low for 15 minutes.
6Boil the rigatoni in salted water at a rolling boil, 1 minute under packet time. Toss with the ragu, 1/2 cup pasta water and half the parmesan on low heat for 2 minutes.
Serve it like this
Spoon rigatoni into a warm bowl so a few tubes stand upright, heap the ragu on top, then add a snow of parmesan and a few coriander leaves.