Heat the stock. Peel and finely chop the onion and garlic. Trim and finely chop the celery. Put 2 tablespoons of olive oil and the knob of butter into a separate pan, add the onion, garlic and celery, and cook very slowly for about 15 minutes without colouring. This is called a soffrito. When the vegetables have softened, add the rice and turn up the heat. The rice will now begin to lightly fry, so keep stirring it. After a minute it will look slightly translucent. Add the vermouth or wine and keep stirring – it will smell fantastic. Any harsh alcohol flavours will evaporate and leave the rice with a tasty essence. Once the vermouth or wine has cooked into the rice, add your first ladle of hot stock and a good pinch of sea salt. Turn the heat down to a simmer so the rice doesn't cook too quickly on the outside. Keep adding ladlefuls of stock, stirring and massaging the creamy starch out of the rice, allowing each ladleful to be absorbed before adding the next. This will take around 15 minutes. Taste the rice to check if it’s cooked. If not, carry on adding stock until the rice is soft but with a slight bite. Don’t forget to check the seasoning carefully. If you run out of stock before the rice is cooked, add some boiling water. Remove from the heat and add the 70g butter and grate in the Parmesan. Stir well. Place a lid on the pan and allow to sit for 2 minutes. This is the most important part of making the perfect risotto, as this is when it becomes amazingly creamy and oozy like it should be. Eat it as soon as possible, while it retains its beautiful texture.