Not all gravy has to be made with flour. The tastiest I've ever had was made of pureed root vegetables: potatoes, turnips, carrots, onions, and garlic. The vegetables were first roasted in the oven with olive oil, sea salt and poultry seasonings; then they were "whizzed" with a mixing wand. Enough water was added to perfect the consistency, and finally the gravy was seasoned again to taste.
This method creates a delicious, lump- and gluten-free, nutritious accompaniment to many main dishes. You can serve this "gravy" on roasts of any kind: pork, beef, chicken, or turkey (with or without the addition of meat drippings). Or serve it on rice, potatoes, or spaghetti squash as a vegetarian option.
Be inventive this Thanksgiving. The most satisfying meals usually exist right at your fingertips.