3 beets with caramelized onions and feta Recipes

cider vinegar, dijon mustard (preferably whole-grain or coarse-grain), black pepper, salt, olive oil, onions (2 medium), quartered lengthwise, then cut crosswise into 1-inch pieces, whole beets, drained and quartered (or halved if very small), crumbled feta (1/2 cup), pine nuts (1 oz), toasted and coarsely chopped

cider vinegar, coarse dijon mustard, salt (or to taste), black pepper (lots of !), olive oil, yellow sweet onion (quartered lengthwise then cut into about 1-inch pieces), sugar, whole fresh small beets, peeled (roasted or boiled, or use as many beets as you wish), crumbled feta cheese (or to taste), toasted walnuts (optional)