Marinated Walla Walla Onions Try these in salads, on burgers, or sandwiches. One Walla Walla Onion, peeled, cut in half, and sliced into thin 1/2 moons 1/3 cup red wine vinegar 1/4 cup sugar 1/4 cup vegetable oil Pinch of red pepper flakes 1/2 teaspoon dried oregano 1/2 teaspoon salt 1/4 teaspoon freshly ground black …