You can make this relish several days in advance because it stores well in the refrigerator for up to two weeks. Serve the relish with the cashew cheese or on the side of the cheese as a separate dish.
Soak cranberries in wine. Set aside.
Heat nonstick skillet over medium-high heat. When hot, add mustard seeds, and toast until seeds begin to pop. Remove pan from heat, and add oil, onions, garlic, ginger and cayenne.
Return pan to heat, and sauté mixture until onions are translucent. Add sugar, salt and cranberries with soaking liquid. Cook mixture until it just boils. Reduce liquid by half. Add vinegar, remove from heat and cool completely.