8 well-trimmed rib racks of lamb, about 3 pounds
kosher or sea salt
freshly ground black pepper
2 tablespoons olive oil
1 large onion, finely chopped
1/2 cup Tawny Port
1/4 cup fresh orange juice
1-1/2 teaspoons red-wine vinegar, or to taste
1-1/2 cups cherry preserves
Heat oven to 425°.
Season lamb chops on both sides with salt and pepper. In a medium, ovenproof sauté pan over medium-high heat, sear lamb chops in oil on both sides. Remove lamb to a plate and lower heat to medium. Add onion and gently sauté until softened but not browned. Add Port, orange juice, and vinegar; simmer, stirring, 2 minutes.
Add preserves and stir well. Nestle lamb into pan sauce (adding any juices that have accumulated on the plate) and bring to a boil.
Transfer pan to oven for 15 minutes. Remove meat to a cutting board and let rest, loosely covered with foil, 10 minutes.
While lamb is resting, simmer sauce, stirring, until slightly thickened and reduced to about 2 cups. Place lamb chops on serving plate and spoon sauce over them.