Mix garlic and salt into a paste.
Stir in the yogurt, lemon and pepper.
Skin the chicken breasts. Remove all extra fat and split into halves.
Make the halves lay flat by bending backwards to separate the bones.
Coat each half with the yogurt mixture.
Cover the bowl tightly and place in refrigerator to marinate for at least 12 hours, no longer then 36 hours.
Turn the pieces over about half-way through marinating.
When you are ready to cook, remove the breasts from the marinade and wipe off most of the yogurt. Leave a thin film on each piece.
Grill about 6 inches above the heat for about 6 to 8 minutes a side. ( or until completely cooked. )
Serve while still hot.