1. Place a large cast iron skillet or straight-sided sauté pan on the stove. Fill with canola or vegetable oil until it reaches two to three inches high. Heat over medium heat until it reaches 350 degrees (measure using a deep-fry thermometer).
2. Into a medium bowl, combine the flour, cornstarch, baking powder, and salt, whisking to combine. Add ice water and vodka, continuing to whisk until the mixture is completely smooth.
3. Dip chicken into the batter, one piece at a time, allowing excess to drip off. Carefully place in the hot oil. Cook in 350 degree oil, about five minutes on each side, until coating is crisp but not browned (the chicken will not be fully cooked). Remove and place on the second cooling rack on a baking sheet. Repeat with remaining pieces of chicken.
4. Raise the heat under the pan so the oil reaches 375 degrees. Working in batches, return the chicken to the pan and fry again, this time until the coating is light brown and very crispy, about 4 minutes on each side. Once cooked, return the chicken to the second cooling rack. Repeat with remaining pieces of chicken.