In a large bowl, combine 1 large egg and ⅓ cup black sugar, and whisk together until sugar has dissolved.
Add 1 tsp oil and whisk together.
Sift 1 cup cake flour, 1 tsp baking powder, and ⅛ tsp kosher salt over the egg and sugar mixture.
Using a silicone spatula, start to combine the dry and wet ingredients. If the dough is too wet, you can add extra flour. Moisture in the air effects, so you have to decide how your dough is like. If you feel that it’s too soft and wet, add more flour 1 Tbsp at a time. The consistency is similar to cookie dough, but slightly softer. Let the dough rest for an hour.
Bring the oil in the deep fryer to 300-320ºF (150-160ºC) over medium-low heat. In order to cook inside the dough, we deep fry at low temperature. For a medium saucepan, you will need about 3 cups of oil. You can use less oil, but you will need to rotate the balls often as they won’t be covered by oil.
Prepare some oil (for rolling the dough) in a small bowl and rub it on your palms which will prevent the dough from sticking to your hands.
When the oil in the deep fryer reaches 300-320ºF (150-160ºC), scoop the dough with a cookie scooper and roll into a ball. To achieve the same portion size for whatever you're making, a cookie scooper is a great tool to have. The size should be slightly bigger than 1 inch (should be around 3 cm). We say the size should be Ping-Pong ball size (if that helps).
As soon as you are done with rolling, start putting the dough balls into the oil. They will expand so do not put too many.
Once the dough balls are cooked through, they start to float. They rotate themselves, but you can help them rotate to achieve even coloring.
When golden brown, about 7-8 minutes of deep frying, pick them up and drain excess oil on a paper towel or wire rack. Let cool for 5 minutes and enjoy!
You can store the leftovers in the refrigerator for 3 days and in the freezer for 2 weeks.