Place chicken breasts in large ziplock bag and pound a little to tenderize, but not necessarily to flatten out. Then put in a fresh ziplock bag that you're sure has no holes in it. Place that in a large bowl.
Place first four ingredients in a bowl and whisk till blended. Pour over chicken, zip bag shut and place in refrigerator for about 2 hours.
Pour off marinade into a small saucepan and boil it to use as a sauce. If you boil it, it's OK to consume even though it had raw chicken in it. Grill chicken on outdoor grill or indoor broiler till done. Pour marinade sauce over it.
If you want to make your own Greek Seasoning Blend, here's how: