Microwave or bake sweet potatoes until tender (for mashing). Cool for a few minutes. Skin will peel off easily, disgard skin and hard ends of potato.
Mash potatoes thoroughly by pushing them through a ricer, food mill or using a large fork or potato masher.
Stir in flour 1/2 cup at a time, until a dough forms. You may not need the last 1/2 cup...the dough will be soft but not sticky.
Break off a piece of dough, and roll with the palms of your hands until you have a rope about as thick as your thumb.
Cut rope into 1" pieces. Take each bit of dough and lightly push down against the inside of a fork as you "flip" it onto the board (or if you have one, use a butter paddle, which you can find in some speciality food shops). This will cause the gnocchi to take on a concave shape with ridges on the outside, which will ‘catch’ any kind of sauce you put on them.
Place your gnocchi on a lightly floured baking sheet as you make them. (If you want to freeze them, place sheets in freezer until gnocchi are frozen and then place them in a freezer bag and store until ready to use. Do not defrost before boiling them.)
Cook them in a gently boiling, well-salted water. They are done just as soon as they rise to the surface of the water. Transfer to a serving bowl immediately and pour sauce over them, stirring them gently to cover all.