Step 1Place 9 cloves, the cumin seeds, 1 cinnamon stick, 3 garlic cloves, the chiles, turmeric, 18 peppercorns and the vinegar in a blender. Blend on high speed until as smooth as possible, about 4 to 5 minutes. Add the water and blend just to combine. Set aside.
Step 2Place the remaining garlic and the ginger in a small food processor along with about 1 tablespoon of water. Process until a paste is formed. Set aside.
Step 3Heat the oil in a large saucepan over high heat. Add the onions, remaining cloves, remaining cinnamon stick and remaining peppercorns. Cook, stirring often, until the onions have browned, about 15 minutes. Add the mixture from the blender, the ginger-garlic paste and the potato and continue to cook over high heat until the mixture thickens a bit and the potato is almost cooked through, 10 to 15 minutes. Add more water if the curry thickens too much. Add the shrimp, salt and sugar and cook another 5 minutes, stirring, until the shrimp are cooked through.
Substitute 1 1/2 pounds boneless pork, cut into small cubes, for the shrimp. Prepare the sauce as for Shrimp Vindaloo, add the pork and cook over low heat 1 hour. Cool and refrigerate overnight. Reheat and serve. 4 servings.