I have a raw fruit relish that I'd like to like to thicken into more of a jam consistency.  I'm thinking about heating in a saucepan with some cornstarch or syrup, but I don't have any idea how much cornstarch to use, and I don't want to mess this up.  What approach should I take to thicken this relish?  Here is the recipe for the relish:        2 pounds fresh cranberries   1 cup sugar   1/4 cup Grand Marnier liqueur   1 orange, zested and juiced         Place all the ingredients in the bowl of a food processor, pulse   several times to breakdown the cranberries and incorporate the   ingredients; it should still be a bit chunky. Allow the cranberry   relish to sit at room temperature for at least 30 minutes, so the   flavors can marry.   From Fresh Cranberry Relish by Tyler Florence and JoAnn Cianciulli. 
Cranberries have a ton of pectin- which is one reason why cranberry jelly is so prevalent.  Just simmer the cranberries, sugar, and orange juice together for a while and they will eventually gel. I don't know how the liqueur will behave but if it was supposed to be served raw then you probably would want to add it after boiling so the alcohol wouldn't boil off.  Of course- you won't be able to call this a "raw fruit relish" anymore- it would become a pretty standard cranberry sauce recipe.  If you want to keep the berries raw then I would recommend combining the sugar and orange juice with some other thickener such as corn starch or gelatin. 