Heat oven to 350°, place hazelnuts on a small sheet pan and cook for 10 to 15 minutes. Let cool, then remove the skin by rolling with your hand. Coarsely chop and set aside.
Place butter, brown sugar, and chopped onion into a skillet on medium heat. Bring to a boil and cook for 4 minutes. Remove from the heat and add 2 teaspoons cider vinegar and set aside.
Place cranberries, raisins, red wine, and pie spice into a large sauce pan or dutch oven on medium high heat. Bring to a boil, reduce the heat to medium, and cook for 5 minutes, stirring occasionally.
Next, stir in the reserved sauteed onion and the additional 1/4 cup sugar, (or maple syrup), and cook for another 10 minutes. Stir occasionally.
Remove from the heat and add the chopped hazelnuts and stir to combine. Taste and add a small amount of salt if desired. Allow to cool before serving warm.
Notes
Make this up to 2 weeks before serving, stored sealed and refrigerated. Reheat slightly before serving.Freeze in freezer bags up to 2 months. Defrost in the refrigerator overnight.Fresh cranberries can be bought in season, (Sept. thru Jan.), and kept frozen for up to a year. This recipe makes about a quart of sauce, (8, one half cup servings). The recipe card has a slider to increase or decrease the quantity as desired. Find it under servings above. It will automatically adjust the ingredient quantities.