For marinade base, place the onions, garlic and 1/2 cup cider vinegar in a blender and puree. Place puree in mixing bowl. Add the mustard, white pepper, garlic power, sugar & salt. Beat in oil with mixer at medium speed, then gradually add the additional 3/4 cup vinegar, mixing thoroughly.
To the base add the marinade spices and water. Blend thoroughly. Makes about 1 quart, enough for 2-2 pound chickens.
To cook, immerse split chicken or chicken parts briefly in the marinade (about 20 minutes, but I have marinaded over night too) Place chicken on sheet pan and bake in 350 degree oven. 1 chicken split will take 1 to 1 1/2 hours. Chicken parts will take 45 minutes to 1 hour.