Boil the diced sweet potatoes until they can be easily pierced with a fork
Combine the boiled sweet potatoes with the salt, sugar, and baking powder in a food processor (you may need to work in batches if your food processor is small)
Transfer the processed mixture to a very large mixing bowl. While the mixture is still hot, add the all-purpose flour and gradually add the cornmeal. Mix with your hands as you go. The mixture should feel like play-doh once it's all mixed together, but not be so dry that it falls apart while you're rolling it. Try rolling a small amount, and add more cornmeal if the dough is too sticky. You may not use all of the cornmeal, it's ok if you have a small amount left over.
Rub a small amount of oil between your palms, and roll each gufong (2 tablespoons of the mixture at a time) into a log/hot dog shape, set the gufong on a plate and repeat until you've rolled out all of the gufong (there will be 40-50 of them). Keep the dough and the rolled gufong covered with a damp cloth prior to frying them, so they don't dry out.
Heat the oil in a deep pot or dutch oven, until it reaches 325°F. Drop 6 gufong into the oil at a time and fry them in batches until they are deep golden color (about 4 minutes per batch). The gufong should be firm on the outside when they come out of the oil, and the centers will be warm and soft. They will firm up slightly as they cool.
Cool the gufong on a wire rack and serve them while they are fresh. Gufong can be stored at room temperature in a paper bag or in a bowl covered in foil. They are best when eaten within 2 days.