Finely chop the onion and stir fry it on medium-low heat.
The rice is first cooked briefly in a soffrito of onion and half of the olive oil to coat each grain in a film of fat, called tostatura.
When the rice starts to get brown, add the white wine, which needs to be absorbed by the grains.
When it has been absorbed, raise the heat to medium-high, and add boiling vegetable stock gradually in small amounts while stirring constantly. With only a tiny amount of liquid present, the constant stirring forces the grains to rub against each other and release the starch from the outside of the grains into the surrounding liquid, making it creamy.
When the rice is half-cooked, add the saffron and stir until the rice looks evenly yellow.
When the rice is cooked al dente, we take the pot off the heat for mantecatura. Add the remaining olive oil (or butter) and the nutritional yeast (or grated parmesan cheese).
Let it rest two minutes before serving.