If you haven’t harvested all of your rhubarb yet then you can still cut some and make homemade rhubarb vinegar. It looks like it is a fairly simple process, clean rhubarb, cut up, let it sit in wine vinegar and when it is all done you can used it make salad dressings or use it where you might use apple cider vinegar or any other fruit vinegar.
If you still have lots of rhubarb you would like to do something with, here are a couple of more ways to use it. You could make some delicious and good for you Fermented Rhubarb Honey Soda Recipe, it is lacto fermented and so it is chock full of probiotics or you could make Home Canned Stewed Rhubarb so you can get it put up and then wait till later to make something with it and don’t throw away the leaves because you can use them to make a Rhubarb Leaf Pesticide Spray and not waste any of the harvest, best of all it will come back and provide more next year.