1. Peel, core, and slice apples about 1/4 inch thick to make about 8 cups. Put slices in a 6- to 8-quart pan.
2. Trim and discard chili stems. For less heat, discard chili seeds. Finely chop chilies; add to apples.
3. Also add vinegar, sugar, raisins, onion, ginger, garlic, and mustard seed. Bring to a boil over high heat. Reduce heat and simmer, stirring occasionally, until apples are very soft when pierced and juice is syrupy, about 1 1/2 hours.
4. Serve warm or cool. Cover airtight and store in the refrigerator.
Nutritional analysis per 1/4 cup.