Heat olive oil in a large pot over medium heat. Add the garlic and onions and cook until soft, about 3-4 minutes.
Add the lentils, sweet potato, water, coconut milk, tomato sauce, and seasonings. Stir until combined. Let simmer over low-medium heat until the lentils are cooked and the sweet potato is soft, about 33-36 minutes.
Add the chopped kale about 3-5 minutes before the soup is done cooking.
Remove the soup from the heat and let stand about 10 minutes to thicken.
Serve immediately or store in the fridge for up to 1 week.
Notes
I soak and drain my lentils in water for 4-6 hours before cooking. If you are using dried lentils, you may need to add more water throughout the cooking process.