First of all, it should be clear whether the optimal temperature refers to the temperature of the oil or the center temperature of the steak; secondly, using different oils, the applicable oil temperature is different. If you use butter, the oil temperature should be around 120℃, because above this temperature, the butter is smoking; if you use olive oil, the oil temperature should be around 180℃; if you use peanut oil, the oil temperature should be around 200℃. Therefore, the proper oil temperature should be controlled according to the oil used. The center temperature of the fried steak, if it is fully cooked, is at 80~90℃.