Heat 2 tsps oil in large oven-safe skillet. Add chicken, and nicely brown each side - about 2 minutes per side.
Remove from heat.
Layer on top of the chicken:
slices of fresh lemon
red onion
artichoke hearts
Pour Greek dressing over the top, coating everything well.
Place pan in the oven. Bake about 30 minutes, until juices run clear & no longer pink in the middle. Bake time depends on the size breasts, and the pan you are using.