1. Cut the chicken thighs into about 2-inch pieces. Just try to get them as close to the same size as possible, so they cook evenly.
2. Slice the onion into slices and separate the rings. Place the meat and the onion rings in a bowl.
3. Add salt, pepper and enough white vinegar to completely cover the chicken. Cover the bowl and let marinade for about 4 hours or overnight. (Refrigerate)
4. When ready to grill…
Skewer the chicken alternating with onion rings. Grease the grill and cook the shish kebabs until completely done, turning over to evenly cook on all sides.