Whisk flour and chili powder into water in a medium bowl. Add salt and cumin powder. Add to a heavy sauce pan and bring to a boil over medium high heat, stirring occasionally. Once the sauce boils, reduce the heat to a simmer and cook for 3-4 minutes, stirring constantly to prevent sticking or burning. Set aside while you make the filling. In a heavy skillet, heat the canola oil over medium heat. Add green onions and saute for one minute. Add tofu, salt, soy sauce ad cook another 2-3 minutes. Reserve. Preheat oven to 350 degrees. Using metal tongs to hold them, cook tortillas over an open gas flame to soften. They can also be wrapped in a cloth towel and microwaved on high for 3-4 minutes. Fill each tortilla with about 1/3 C. filling and roll up from one side to another. Place seam side down on a 10-inch round baking dish coated with cooking spray. Once they are filled, cover with sauce, and cover with aluminum foil. Bake in a preheated oven for 25 minutes. Remove foil, sprinkle with cheese and bake another 5 minutes.