I brown the sausage up, then remove from the pan, reserving the fat in the pan. I add the flour, about 1/2 to 3/4 the amount of flour to oil in the pan, then cook until tan, I then add finely chopped onion, maybe 1/4 cup and cook that into the roux. I like to use 1/2 water and 1/2 milk, until right consistency is achieved. Then add sausage back in. If I am going to hold the gravy, I store it in zip closure bags with air pressed out. Prevents formation of a skin.
I'm feeling bearish, and I'm packing a Wusthof Grand Brisket slicer from MABA
"perhaps...but then again...maybe not..."