Place the first 6 ingredients in a 5- or 6-quart slow cooker., In a skillet, heat oil over medium heat. Add garlic, paprika, ginger, cumin, salt, pepper and cinnamon; cook and stir until fragrant, about 1 minute. Add tomatoes, harissa and honey; bring to a boil. Pour tomato mixture over vegetables; stir to combine. Cook, covered, on low until vegetables are tender and sauce has thickened, 4-5 hours. Stir in mint. , If desired, top with yogurt, and additional mint, olive oil and honey to serve.