Get the chicken breasts onto a board. Decide if you want to pound them in which case cover with plastic wrap and gently pound starting on the thicker side of the breast and work to get them more or less the same size right round. They will cook more evenly. Otherwise move onto the next step.

Combine the oil, vinegar, salt & pepper and chicken spice.

In a wide flat bowl add chicken breasts and pour the marinade over. Use a pair of tongs to flip them over a few times until well soaked. Let them sit for 5 minutes.

Meanwhile heat the grill pan on medium to high heat and let it get hot. Once hot brush the base with some oil and increase the heat to high. Give it a few seconds on high till hotter, brush another coat of oil and immediately place the chicken breasts down.

Let them cook for 3 to 4 minutes without moving them. In the last minute pour a little of the marinade on and turn them over to continue cooking for another 3 to 4 minutes on the opposite side.

After a minute or 2 of cooking baste/pour some of the marinade over and let them finish cooking till done, about 2 more minutes.

Remove and place on a board to rest till cool before cutting into them. Use any remaining marinade to pour over. Enjoy!