To make the gravy, cut the seitan into chunks, and feed through a meat grinder on the larger die setting. If you do not have a meat grinder, you can chop up the seitan sausage into small chunks, and add it to a food processor and pulse it until it reaches the desired consistency.
Add the ground sausage and oil to into a pan, and cook on medium low until browned. You want to impart flavor into the oil as much as you want the oil to help the sausage brown.
Once browned, sprinkle the flour over the sausage, a tablespoon at a time, and stir, forming a roux. Cook for 3-4 minutes, or just until the flour barely starts to brown. Add about a cup of the soy milk slowly to the pan, and stir vigorously. You will wind up with a very thick mixture. Stir until there are no lumps. Add the rest of the milk and bring to a simmer. Cook for 10 to 12 minutes, or until it reaches your desired thickness. If the gravy is too thick, add more soy milk to thin it out. If it is too thin, continue to simmer until it is reduced.
Serve warm over your favorite biscuits.