1. Heat a large pot over medium heat. Add a splash of oil, then add the diced onion. Cook until softened, about 5 minutes.
2. Add the minced garlic and grated ginger. Cook for another 2 minutes.
3. Stir in the cumin, coriander, and turmeric. Cook for 1 minute until fragrant.
4. Add the diced sweet potatoes, chopped collard greens, diced tomatoes, and vegetable broth. Bring to a boil, then reduce to a simmer. Cook for 20 minutes, or until the sweet potatoes are tender.
5. Stir in the peanut butter until well combined. Season with salt and black pepper to taste. Cook for another 5 minutes.
6. Serve hot, garnished with fresh herbs if desired.
Notes:
This stew is perfect for a cozy dinner and pairs well with rice or flatbread.