1. Place onion, raisins, prunes, ginger, vinegar, sugar, cumin, salt, and 2 cups water in a low-sided, 6-quart saucepan. Set over medium-high heat, and bring to a boil.

2. Reduce to heat to medium-low, and simmer, stirring occasionally, until most of the liquid has been absorbed, about 40 minutes.

3. Add the apples and 1 1/2 cups water. Cook, stirring frequently, until apples are soft and translucent and liquid has been absorbed, about 50 minutes. Remove pan from heat.

4. Transfer to a large bowl set over an ice bath to chill, and store in airtight container, refrigerated, up to 4 weeks.