combine the seasoning mix ingredients in a small bowl and set aside.
In a blender, pour can of vegetable soup and puree. Once smooth, add water to 3 cups. Re-puree until smooth. Set aside.
In a separate bowl combine the onions, celery, and bell peppers. In a large skillet (preferably cast iron), heat the oil over high heat until it begins to smoke, about 4 minutes.
Gradually whisk in the flour , stirring until smooth.
Continue cooking, whisking constantly, until roux is dark brown, about 3-5 minutes.
Remove from heat and immediately stir in the vegetables and 1 T of the seasoning mix with a wooden spoon; continue stirring until cooled, about 5 minutes. In a 2-qt saucepan bring 2 cups of the vegetable soup mixture to a boil over high heat.
Gradually add the roux and whisk until thoroughly dissolved all the time reducing the temp to prevent scorching of overboil.
Reduce heat to low and cook until flour taste is gone, about 2 minutes, whisking almost constantly.
Remove from heat and set aside. In a 4-qt saucepan melt 1 stick of butter over medium heat.
Stir in shrimp and saute 1 minute, stirring constantly.
Add the remaining stick of butter, the puree mixture and the remaining 1 cup puree; cook until butter melts and is mixed into the sauce, about 4-6 minutes, constantly stirring to prevent sticking/scorching/burning.
Add the remaining seasoning mix, stir well and remove from heat.