Cut the chicken into strips and pour half of the marinade onto the chicken, just enough to cover it. Marinate for at least 10 minutes. Reserve the other half of the marinade for a later use.
For the plate: Heat up a saute pan over medium heat. Sprinkle the marinated chicken with salt and pepper. Add the olive oil to the pan and saute the chicken until fully cooked, about 5 minutes.
To build the sandwiches, split both loaves of bread open. Add the chicken, sliced tomatoes and onions. Place some mixed greens on top, and then drizzle the reserved marinade to finish. Slice the sandwiches in half and enjoy.