In a large sauté pan, heat the oil over medium-high heat. Add the onions and cook until fragrant. Add the sweet potato, garlic, peppers, thyme, salt, and pepper. Stir for 30 seconds.
Add the coconut milk and the water. Cook, stirring until the sweet potatoes are tender and the liquid is slightly reduced, about 10 minutes.
Add the greens and stir until wilted. Remove from the heat and adjust the seasonings as needed.