In a medium sized sauce pan add the sauce ingredients and cook on a medium heat, bringing the sauce to a simmer.
Cook the sauce at a simmer for about 10 to 15 minutes, stirring as it cooks.
As the sauce is cooking it will start to thicken.
After it is done cooking remove from heat and set aside.
Clean and slice the mushrooms, set aside.
In a large skillet, add oil and mushrooms, saute on medium high heat until the mushrooms are slightly browned.
Next, pour 3/4 cup of the cooked barbecue sauce over the sauteed mushrooms, you can use less or more if you prefer.
Save any left over barbecue sauce for later use as a condiment.
Stir until everything is covered, cook for another 5 minutes, remove from heat and set aside.
Toast your bread or bun, smear your favorite mayo, or vegan mayo, on the toast, add cheese, sliced pickles, and serve.