1/4 cup aged balsamic vinegar
1/4 cup white wine vinegar
1 tablespoon Chardonnay wine
2 tablespoons white sugar (optional)
1 (15 ounce) can sliced beets, drained and cut into 1/4 inch slivers
1/4 cup thinly sliced red onions
4 cups chopped fresh spinach (optional)
Whisk together the balsamic vinegar, white wine vinegar, Chardonnay, and sugar in a small bowl. Place the beets and onions in a small, sealable container. Pour the vinegar mixture over the beets and onions to completely cover. Seal top; marinate in refrigerator for 4 to 5 hours.
When ready to serve, divide spinach leaves between four salad plates. Top with beet mixture, and drizzle salads with a bit of the marinating liquid.