Blueberries in the salad and in the infused vinegar contribute antioxidants. Start early on this recipe in order to make the fresh blueberry vinegar. Store leftover infused vinegar in the refrigerator for up to two weeks; use it as part of a marinade for pork, chicken thighs, or duck.
Combine Blueberry Vinegar, honey, mustard, salt, and pepper in a small bowl. Gradually add oil, stirring with a whisk. Combine arugula, frisée, blueberries, and onion in a large bowl. Arrange 1 cup salad onto each of 6 plates; drizzle 1 tablespoon vinegar mixture onto each serving.