1. Fill a saucepan with about 2 cups of water and bring to a boil. Prep the asparagus by breaking off the ends where they naturally snap. Place the trimmed stalks in a steamer basket above the pan of boiling water and add the snapped-off ends into the water itself. The trimmed stalks should be cooked al dente — do not let them get soft. (This will only take a few minutes.) Leave the ends simmering away until they’re well-cooked.
2. Cut the tips off the stalks and set aside as a garnish. Cut the remaining asparagus stalks in half. Reserve half, slice the rest into tiny rounds, and set aside. Turn off the heat under the simmering asparagus ends, fish them out, and discard. DON'T THROW AWAY THE WATER. You'll use it to make the risotto later.
3. Blend the batch of halved asparagus stalks, peas, almost half of the butter, ½ cup (100 ml) of the stock, plus a spoonful of the asparagus cooking water to a pale green purée using a stick blender or food processor. Taste and season with salt and black pepper. Set aside.
4. To make the risotto, gently sweat the chopped onion or shallots in the remaining butter over medium-low heat. When the onion has softened (10 minutes or so). Add the rice (it should sizzle as it hits the pan) and the white wine or vermouth. Cook the alcohol until it has all been absorbed by the rice, stirring to make sure it does not stick.
5. Begin adding the stock (including the asparagus cooking water too), one ladleful at a time. Add more stock as the previous gets absorbed by the rice. Stir all the time so the rice doesn’t stick. This takes about 20 minutes, but it’s worth the effort.
(I recommend the radio in the background, with a glass of wine in one hand and a wooden spoon in the other.)
6. Add the little asparagus rounds about 5 minutes before the risotto is ready. To finish, beat in the Parmesan and butter with a wooden spoon. This is a vital stage of risotto making, which ensures a glossy, smooth finish.
Check the seasoning. It’ll probably need lots more salt and black pepper. Just before serving, warm the asparagus purée in a small pan, then stir it in so it streaks the risotto. Garnish each plate with the reserved asparagus tips.