Basicly Tim, what I do is to kind of Season the roast, and Brown It in a very little bit of Olive oil (any Oil will work) , when it starts getting Brown that's when i add the roast to the Slow Cooker. with spices.
When It's about half way done, I'll add my Veggies (Lot's of potatoes and Onions personaly) and Let it finish. I do use Corn Starch or Flour, But only to thicken the Gravy for the roast.
It might not be Pretty, But It fills my Tum Tum.
Stephen