Onion finely chopped and fry in a skillet in butter until then, until the onion starts to smell fried, add finely chopped mushrooms and fry them until they release the water. Then pour the rice in a saucepan and fry it with onions and mushrooms for two minutes, stirring constantly.
Pour the rice and onions chicken broth and wine. Cook without a lid, stirring constantly. When the broth and wine to evaporate by half, add a tiny pinch of saffron and salt. Stir and cook until the rice is cooked. If the liquid boils away too soon, pour water, wine or broth.