Pat the chicken dry with paper towels and place in a bowl. Season with salt and pepper; toss to coat. Add the cornstarch; toss to thoroughly coat. In the same pan, heat a thin layer of oil on high until hot. Once the oil is hot enough that a pinch of cornstarch sizzles immediately when added to the pan, add the coated chicken (shaking off any excess cornstarch) in a single, even layer. Cook 3 to 5 minutes on the first side, or until golden brown. Turn and cook, without stirring, 2 to 3 minutes, or until browned and cooked through.