Sprinkle lamb with salt and pepper. Place in a slow cooker. Sprinkle with the parsley, garlic, oregano and lemon zest.
In a small saucepan, saute the onion and carrot in oil for 3-4 minutes or until tender. Stir in wine and beef stock concentrate. Bring to the boil, stirring occasionally. Pour over lamb. Cover and cook on low for 8 hours or until meat is tender.
Remove lamb and keep warm. Strain cooking juices and skim fat. In a small saucepan, bring juices to the boil; cook until liquid is reduced by half. Serve with lamb.