prepare the saffron
Stir to combine saffron and hot water in a small bowl. Set aside for 15 minutes.
cook the rice
Place a medium pot over medium heat. Add olive oil and diced onion. Cook for 5 - 8 minutes for the onion to soften, stirring occasionally. Add the rice and cook for another 5 minutes.
cook the risotto
Increase the heat and add white wine to the rice. Cook for 2 minutes for the alcohol to evaporate. Gradually, ladle by ladle, and start adding the vegetable broth. Add the next ladle of broth only when the first one is cooked into the rice. Repeat the process until the rice almost cooks. It will take about 14 - 16 minutes. Make sure to stir the risotto regularly.
finish and serve
Remove the risotto from the heat and stir the butter and grated parmesan cheese. Season to taste with salt and pepper. Cover with a lid and set aside for 3 minutes, then serve.