Peel and cube potatoes. In food processor, process garlic and 1 tablespoon water to a paste. Roast chile, coriander seeds, peppercorns and fenugreek in a dry pan over moderate heat until fragrant. Process mixture in spice grinder. Stir in turmer and set aside. Heat oil in skillet. Add mustard seeds and stir until they pop about 5 seconds. Add onion and fry for 5 minutes. Add garlic and fry for 1 minute. Add potatoes, salt and pepper. Stir for 2 minutes or until potatoes are lightly browned. Add spice mixture, stir for 1 minute and serve over rice.