In your deep-frying vessel (a deep pot is best, in our opinion), heat up oil (5 cup) to 300°F. There should be enough to cover the chicken wings.
Once the oil reaches the right temperature, start cooking the drumettes. They're thicker, so they take longer to cook.
Set the pieces in gently; if you drop things into hot oil from high up, they'll splash dangerously. Instead, set them in gently, and let go once a corner of the piece is actually in the oil. It won't splash, and the splatter won't be very dramatic because your wings are coated in dry flour.
When the drumettes are all in, lower the heat to medium so that the oil can stay more consistently around 300°F. Occasionally, you may need to raise or lower the heat to keep the oil at the right temperature. Flip and rotate the chicken to help it cook evenly. When the chicken turns golden and floats to the surface, it has cooked through. This should take about 5 minutes. Take them out, and then fry the flats. The flats will cook through much faster, normally taking about 2 minutes. Take the flats out.
The chicken wings are now cooked through but not sufficiently crispy, so we're going to fry them a second time to get that crunch! The second fry will also tighten the crust to help keep the interior nice and juicy.
Bring the oil up to 350°F for the second fry. Add the drumettes back into the oil. Let them get a 30-second head start, then add the flats as well. After 30 more seconds, scoop out the golden brown drumettes, which will have had spent a smidge more than 1 minute in the second fry. Once all the drumettes are out, take out the golden brown wings.
Set the pot aside. You'll need to take a bit of it for the next stir-frying step. You can strain and reserve the rest for future use after it cools down a bit.