Boil the sweet potatoes: Remove the skins from 4 large sweet potatoes. Cut into chunks and place in a large stock pot. Add cold water until all of the potatoes are completely submerged. Bring the water and potatoes to a boil over high heat then let them boil, uncovered, for 18-20 minutes, or until the potatoes are easily pierced with a fork. Strain the potatoes and place them in a large mixing bowl. Mash with a potato masher or fork until smooth. Set aside and allow to cool slightly
Form a dough: Combine the cooked potatoes and cassava flour in a large mixing bowl. Stir together with your hands until flour is fully incorporated. Mix and knead until the dough starts to form a ball. If the dough is too wet, continue to add cassava flour a tablespoon at a time until the dough forms a ball and is not too sticky
Form dough into gnocchi: Turn the dough out onto a well floured surface (use more cassava flour for this). Divide the dough into 4 roughly equals parts using a bench scraper or sharp knife. Take one piece and set the other three aside. Roll the dough into a long rope with a 1 inch diameter. Starting at one end, cut the dough into 1 inch pieces and set aside. Repeat this process with the other 3 portions of dough. You can make fork marks on each gnocchi at this point if you want to, but it’s optional
Boil the gnocchi: Fill the same stock pot from the potatoes with water about half way full. Add about 1 teaspoon of salt and heat on high, uncovered until boiling. While it’s heating, place a sheet tray next to the stove on which to set the cooked gnocchi. Once the water is boiling, add 1/4 of the gnocchi to the water. The gnocchi will sink to the bottom. Once they float to the top of the water (about 2 minutes) remove them with a slotted spoon and place on the prepared baking sheet. Repeat the process with the rest of the gnocchi
Cook your gnocchi as desired
Once gnocchi have been boiled, they can be frozen for later use. With gnocchi on sheet tray in a single layer, place in freezer for at least two hours. Once frozen, place gnocchi in a freezer safe ziptop bag. They will keep in the freezer for at least 3 months.