Crumble tofu into a blender or food processor. Puree briefly, then add the soy milk, margarine, garlic, nutritional yeast, paprika, dill and spice blend. Process the mixture until it is smooth.
Pour the mixture into a medium saucepan and cook over medium heat until it comes to a boil. Combine the cornstarch and water, pour into pan with the sauce. Continue cooking over medium heat until sauce has thickened, about 1 minute. Remove from heat and allow sauce to cool slightly, adjust flavors to taste and serve over pasta or roasted vegetables.