Whisk the eggs in a bowl then add sugar. Continue whisking until the sugar is well-combined with the eggs.
Add salt and melted butter into the bowl with eggs then continue mixing.
Combine the baking powder and flour in another bowl then mix well. Add about a third of the amount of the flour and baking powder mixture into the bowl with eggs then mix until the the mixture becomes soft.
Add the rest of the flour then continue mixing until the dough becomes soft.
Pour the oil for deep frying in a deep pan. Turn on the heat then wait until the temperature of the oil reaches 160 C (320 F).
Once the desired temperature of oil is achieved, reduce the heat to low.
Scoop out about a tablespoon of the dough then drop it into the hot oil. Cook until brown and the doughnuts rise to the surface. This takes about 5 minutes.
Once the doughnuts have browned, increase the heat to high then fry until the surface of the doughnuts become crunchy. Remove from pan then drain excess oil then you can serve hot.