In a large pot, heat oil over medium heat. Add onion and sauté for 3-5 minutes, until translucent. Add garlic and ginger. Sauté for 3-4 minutes, until fragrant and golden brown.
Add the potato and cook for 5-8 minutes, until just softening.
Add cumin, cinnamon, cloves, cayenne, and crushed red pepper. Stir thoroughly, and cook for 2 minutes. The spices will stick to the bottom of the pan — that’s ok!
To deglaze the pan, add 1/3 of the tomatoes and stir vigorously. Once you can feel that the spices have come up off the bottom of the pan, add the remaining tomatoes and broth. Bring to a boil.
Add the collard greens. Reduce heat a bit and simmer the soup, stirring occasionally to prevent sticking, until the sweet potatoes and collards are softened to your liking, about 20-25 minutes.
Stir in the peanut butter and heat through. Taste and adjust seasoning with salt and pepper. Serve on its own or with rice, garnished with cilantro and roasted peanuts.