Make a simple brine of 1 cup of salt to 1 gallon of water. The brine will make the chicken nice and moist, tasty with a better texture.
Cut the chicken and half and remove the backbone. Give it a two hour bath to overnight in the brine.
Put the cider vinegar, eggs, salt, black pepper, and poultry seasoning in a blender. Turn blender on high and slowly drizzle the oil in like you are making mayonnaise until it thickens.
Take out a cup. Place the chicken in a gallon bag and pour half a cup in the bag with the chicken and save the other half cup for basting. The remaining sauce can be saved for another chicken and used for BBQ sauce with your meal. Marinate for two hours.*
Get a medium high fire going and grill the chicken flipping and basting every 5 minutes until the liquid runs clear or temperature of 170 in thickest part of the thigh. You could also bake it.**
Notes
*Tip- If you are concerned about the raw egg in the bbq sauce (there is plenty of acid to kill the bacteria) then before you add the egg and oil remove 1/4 cup and mix it with 1/2 cup of mayo for your BBQ sauce.**Tip- point the leg side toward the hottest part of the fire so they cook faster because the breast only need to get to 160 degrees.