To a large bowl, add the flour, cornstarch and seasonings; whisk to combine.
Add at least 3-inches oil to a deep Dutch oven or deep cast iron skillet.
Pre-heat the Dutch oven to 350F.
While the oil heats up, working with one piece of steak at a time, remove it from the buttermilk mixture; gently shake off the excess liquid; coat the steak well in the flour mixture; set it onto a prepared baking sheet which has been lined with a cooling rack.
Repeat this process with all of the steak, working with one piece at a time.
Once all of the steak has been coated, again, working with one piece at a time, dip it once more into the buttermilk mixture until fully submerged; remove and gently shake off the excess liquid.
Coat once again in the flour mixture and place it back onto the cooling rack; it is important to double dredge to get the best crispy batter; this also locks the moisture into the steak.