An electrosurgical system comprising: an electrosurgical instrument including an active electrode and an electrosurgical generator coupled to the electrosurgical instrument and configured to supply electrosurgical energy to tissue through the active electrode, the electrosurgical generator including:impedance sensing circuitry configured to measure impedance of the tissue and a microprocessor configured to determine whether a tissue reaction corresponding to a boiling point of tissue fluid has occurred as a function of a minimum impedance value and a predetermined rise in the impedance, the microprocessor is further configured to generate a target impedance trajectory including a plurality of target impedance values as a function of the measured impedance and a predefined rate of change of the impedance based on the tissue reaction determination.
