In a large saucepan, boil the water. Add the chopped rhubarb, and boil until the rhubarb becomes tender - a few minutes
Take the rhubarb and water over to your food processor, and blend it until smooth
Now, in the same saucepan, add the oil and saute the onion until it is tender. Again - a few minutes
Add the ketchup, brown sugar, syrup, vinegar, Worcestershire sauce ( who can pronounce that word?), mustard, Optional hot sauce, salt, garlic powder, smoked paprika, and your pureed rhubarb and water sauce!
Bring this sauce to a boil, stirring constantly, and then reduce your heat. Allow to simmer on low for about 5 minutes - uncovered
Allow to cool slightly, and transfer this to the food processor, and blend until the onion is all pureed
Transfer the sauce to some mason jars for storing and pouring, and enjoy