This very popular relish is from Gujarat in western India. It makes a wonderful dipping sauce for finger foods. Heat oil in a medium-size skillet over medium-high heat. Add mustard and garlic. Cook, stirring, until mixture starts to brown, about 4 minutes. Add turmeric, cayenne, salt and tomatoes. Stir and cook for 2 minutes. Add vinegar and bring to a boil. Reduce heat, cover, and simmer until thick, about 10 minutes. Spoon into clean jars and seal. Makes 3/4 cup. Note: Stays fresh for several weeks in a covered jar in the refrigerator. PER TABLESPOON: 20 calories, 0 g protein, 3 g carbohydrate, 1 g fat (0 g saturated), 0 mg cholesterol, 93 mg sodium, 1 g fiber. Laxmi Hiremath writing in the San Francisco Chronicle, 6/24/92.