Sprinkle steaks with salt and pepper; set aside. Remove and discard roots, tough outer leaves, and tops from leeks, leaving 2 inches of dark leaves. Set aside.
Combine peach spread and next 4 ingredients in a glass measure. Microwave at HIGH 1 minute; set aside half of mixture.
Coat grill rack with cooking spray; place on grill over medium coals (300° to 350°). Place steaks and leeks on rack; grill, covered, 5 minutes on each side or until steaks are desired degree of doneness, basting often with half of peach mixture. Serve with reserved peach mixture. If desired, garnish with cilantro and lime and peach slices.