Smokey Cheesy Sauce

Up until about a week ago I had never tried a rhubarb. My husband grew up in the Midwest where he said they grew like weeds and as a kid they would pick them, dip in sugar and eat.  They had them at our local co-op last week (maybe they always do, I never noticed) so I opted to buy a single stalk so I could give it a try.  I came home and began a search for every rhubarb recipe I could find and they all had something in common...they required like a pound of rhubarb.  Unsure of what to do with it I let it sit in my fridge until it became limp and sad.  Finally I worked up the courage and took a bite.  Wow!  Was it ever bitter.
Why I decided to put the following ingredients together I am not sure but it turned out delicious, similar to what I remember a smokey Gouda cheese (forgive me if you don't agree, it's been awhile since I have actually tasted one.)  I put this together to make a Sweet Potato Au Gratin but the sauce would most definitely stand alone as a cheese sauce. 

Ingredients
1 tbsp olive oil
1 small red onion pureed
1 stalk rhubarb pureed
1 small apple pureed
1 tsp garlic powder
1 tbsp nutritional yeast
1 tbsp miso
2 tbsp Braggs liquid Aminos
1/4 tsp liquid smoke
approximately 1 cup water
1/3 cup Earth Balance
1/4 cup flour
1 cup vegan sour cream*

Saute red onion, rhubarb and apple in olive oil for 15 minutes over medium low heat.   In a one cup measuring cup mix garlic, nutritional yeast, miso, Braggs and liquid smoke. Add water to garlic mix to equal one cup.  After 15 minutes add Earth Balance to onion.  Once Earth Balance is melted and mixed well, stir in flour so mix is well coated.  Slowly stir in water mix.  Reduce to low heat and stir in sour cream.

*I think cashew cream would go really well but I was out and had sour cream.  For a thicker dip type sauce you could use vegan cream cheese and let refrigerate.