||In a pressure cooker, add onion, carrots and celery followed by the oyster blade. Add 2 cups of boiling water, cover and cook for 2 hours. After 2 hours, take the beef out of the pressure cooker and slice into chunks. Add butter to a pan and fry the beef for 3-4 minutes. Allow the beef to rest for 5 to 6 minutes.
||Add olive oil generously to a pot over medium heat. Add the onions and sweat them until translucent, about 5 minutes. Bring the pan to a medium-high heat. Add the rice and cook for 3 to 4 minutes.
||Add 1 cup hot lamb stock to the rice and stir well. Add the saffron. Allow to cook for 5 minutes.
||Repeat this one more time with the stock. When the second addition of the stock has absorbed and the rice is very creamy, bite a couple grains of rice to be sure it is cooked perfectly. If it is still a little crunchy, add a little more stock and cook the rice for another couple of minutes. When the rice is cooked perfectly, remove it from the heat.
||Add the rice vinegar to the pot until it covers the surface of the rice. Add butter and cook over a medium-high heat, stirring continuously.
||Toss in the Parmigiano-Reggiano. The rice should be creamy but still flow and hold its own shape.
||Serve the oyster blade over a bed of the risotto and garnish with spring onions.