In a food processor combine everything except the red onion. Process on low until all of the ingredients have emulsified (a.k.a. turned creamy and even in texture) and the cranberry is broken up into pieces that are about the size of fresh ground pepper.
Pour the vinaigrette into a dressing bottle, add 1 tsp of finely minced red onion and lightly shake to combine.
Serve immediately or store up to one week in the refrigerator. Shake vigorously between uses.
*Recommended brands are Lakewood Organic and R.W. Knudsen. A cranberry cocktail like Ocean Spray won't work for this recipe as it is less concentrated.