1Spray 5- to 6-quart slow cooker with cooking spray. In slow cooker, mix lentils, onion, olives, broth and water. In small bowl, soak tomatoes in warm water to cover while lentils cook.
2Cover; cook on Low heat setting 5 to 6 hours (or on High heat setting 3 to 4 hours).
3During last hour of cooking, drain tomatoes; stir tomatoes and lemon peel into lentils. Serve lentil mixture topped with cheese and onions. Serve with pita wedges.