How to thicken a raw fruit relish? 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.
If I need one, I usually use guar gum as thickening agent in raw dishes. The result is similar to using corn starch, it is more or less without flavour, but does not need heat to activate. I would probably dissolve some in the orange juice and then mix with the other ingredients.