In a 5- to 6-quart slow cooker, stir together tomatoes and puree, tomato paste, jam, garlic, orange zest, rosemary, ginger, and cinnamon. Season with salt and pepper. Add lamb and potatoes, stirring to combine.
Cover, and cook on low for 8 hours (or on high for 5 hours), until lamb and potatoes are tender. Season again with salt and pepper, if desired. Serve.