Heat a pan, add the onion and cook for 3 minutes. Add a little water only when the onions begin to stick to the pan.
Add mushrooms, sage, basil and salt, and cook for an additional 5 minutes. Again, add a little water only if the veggies start sticking to the pan.
Add the rice flour and stir.
Slowly pour in the water, stirring all the while, and simmer for 7-10 minutes until it becomes thick.
Allow to cool for 15 minutes and then blend until smooth.