2 duck breasts (magrets), each about 1 pound
Salt and ground black pepper
1/2 pound rhubarb, leaves removed, cut in 1/2-inch pieces
1 1/2 tablespoons sugar
1 cup finely chopped red onion
Zest and segments from 2 blood oranges
1 cup dry red wine
1 tablespoon red miso
Heat oven to 175 degrees. With a sharp knife, score the skin side of the duck breasts in a crisscross pattern but do not cut into the flesh. Season with salt and pepper. Heat an ovenproof skillet, preferably cast iron, to very hot. Place duck breasts in pan, skin side down, and sear until browned, about 2 minutes. Remove. Reserve 1 tablespoon of fat and discard rest. Return duck to pan, skin side up, and place in oven for 1 1/2 hours.
Place reserved duck fat in a 10-inch skillet on medium-high heat. Add rhubarb, sprinkle with half the sugar and cook a couple of minutes, until the pieces start to brown but are still somewhat crisp. Remove to a dish. Reduce heat to medium-low. Add onion and sauté slowly until very tender. Stir in orange zest and wine. Simmer until wine is reduced by half. Stir in remaining sugar and the miso. Season with salt and pepper. Set aside.
When duck has finished cooking, remove it to a cutting board, slice it thin on the bias and arrange the slices on a platter. Briefly reheat wine sauce and fold in the rhubarb and orange segments. Check seasonings and spoon sauce alongside duck.