Peel and Chop: Peel 2 cups of cassava and 2 cups of green plantains. Chop them into smaller pieces to help your blender out.
Blend: Add the chopped cassava and plantains to a blender with about 2 cups of water. Blend in batches until you have a very smooth puree.
Microwave: Transfer the puree to a microwave-safe dish, cover it with a plate, and microwave on high for 7 minutes. Stir and check the consistency. If needed, microwave for an additional minute until the mixture is translucent and sticky.
Cool and Knead: Allow the fufu to cool slightly, then knead it with wet hands until smooth and elastic.