Heat oil in heavy medium nonstick skillet over medium-high heat. Sprinkle lamb with salt and pepper. Add lamb to skillet; cook to desired doneness, turning often, about 10 minutes for medium-rare. Transfer lamb to plate. Pour off drippings from skillet. Add shallots to same skillet; sauté 1 minute. Add Port, broth, cherries, jam, vinegar, and cardamom; boil until cherries plump and liquid is syrupy, about 6 minutes. Season with salt and pepper. Spoon sauce over lamb. Sprinkle with mint.
