Place the lentils, onion, garlic, carrots, vegetable broth, curry powder, turmeric, and salt in the slow cooker.
Stir everything together until the spices are evenly distributed.
Cover and cook on low for 6 hours, or until the lentils are soft and the soup has thickened.
Pour in the coconut milk and stir well. Cook for another 30 minutes on low to warm through and blend the flavors.
Ladle into bowls and add cilantro and a squeeze of lime just before serving.