In a large saucepan, combine brown sugar, vinegar, ginger, onion, mustard seeds, chili powder, salt and garlic. Stir in the peaches and raisins. Bring to boiling over medium heat, stirring occasionally. Reduce heat; boil gently, uncovered, about 2 hours or until deep golden brown and thick, stirring more frequently at the end to prevent sticking. There will be some liquid remaining but the mixture will thicken further as it cools.

Transfer mixture to a medium bowl. Loosely cover and chill for several hours or until completely cool. Cover and store in the refrigerator for up to 2 weeks. Makes about 2-1/4 cups (36, 1-tablespoon servings).