Most kids I knew growing up ate peanut butter and jelly sandwiches with gloppy grape jelly.  In my house, we grew up eating them with delicious sweet tart rhubarb jam.  This was because my father developed an allergy to most fruits when he was young, with the exception of melons, limes and rhubarb.  My Mom had to get creative with a jam that he could safely enjoy. Technically, rhubarb is a vegetable, with an inedible leaf and a long reddish stalk that looks similar to celery, though it is not related.  But it can be cooked down with sugar and turned into delicious baked treats, or made into a delicious…