In a large pot of boiling salted water, add the cassava and cook 10 minutes. Then add the sweet potatoes and cook with the cassava until fork tender, about 15 more minutes.

While the cassava and sweet potatoes are cooking, heat the olive oil and cook the onions until translucent, about 5 minutes. Add the ginger, crushed red pepper, cayenne pepper and tomato paste, and stir until well blended and fragrant, about 5 more minutes. Add the water and peanut butter and bring to a boil.

Transfer the boiled and drained cassava and sweet potatoes over the tomato sauce, add the spinach and stir to combine. Simmer for 10 minutes until the sauce reduces.