Make the vegetable broth with the onion, carrot, and celery, and let it boil for about 20 minutes.

After this time, put the oil and finely chopped green onion in a pan, let it soften, and add the leeks cut into thin slices.

Mix everything well and let it cook on low heat for about 10 minutes.

Once the leeks are nicely softened, add the rice, mix well, and let it cook for a few minutes.

Now start adding the vegetable broth little by little and cook until done.

One minute before the risotto is ready, turn off the heat, move the pan, and add the saffron, grated Parmesan, and butter, and stir well.

Plate and serve.