Place a small amount of the sweet potatoes in a food processor and pulse until the potato pieces are about the size of dried rice; repeat procedure with remaining potatoes until they are similar in size. Add the yellow onions to the last batch of potatoes to be processed. Combined remaining ingredients and add to processed potatoes in a large bowl; mix thoroughly and spoon potato batter into a skillet and fry with 1/8 inch of oil over medium heat; brown both sides and serve hot.