Melt ghee & stir-fry ginger, garlic & onion for 1 minute. Add flour & continue to stir fry for fro 3 to 5 minutes, till golden in colour. Add water a little at a time, whisking constantly to keep it smooth. Add vegetables, tomatoes, tofu, green onions & bring to a boil. Add the remaining ingredients. Simmer for 10 minutes. Thin with extra water if too thick. Serve hot. Adapted from Betty Jung, "The Kopan Cookbook"