Heat a large saucepan over medium heat and add oil, swirling to coat the bottom of the pot. Add leeks and sauté for a couple of minutes until softened but not browned. Add the FODY BBQ Sauce, rhubarb, brown sugar, molasses, vinegar, celery seed, cumin, smoked paprika and as much chipotle pepper as you like and stir together well. Add some salt and several grinds of black pepper.
Adjust heat and simmer, covered, until rhubarb is soft, about 10 minutes. Adjust salt and pepper and any other seasoning you might want.
I have made this sauce a few times and have on occasion doubled the amount of FODY BBQ Sauce and used 2 bottles with the same amount of other ingredients. The first time I did this I needed lots of sauce and didn’t have time to start from scratch. So I simply added another bottle of sauce to the simmering pot of sauce and it worked very well! So if you want more rhubarb flavor, make it as described above. If you need lots of sauce or just love the flavor from the bottled sauce, add another bottle!