Serves 8
For the risotto
2 lbs/910 g asparagus
2 tsp kosher salt
1 Parmigiano-Reggiano rind
6 tbsp/85 g unsalted butter
1 tsp freshly ground black pepper
1 medium red onion, finely chopped
2 cups/200 g Arborio rice
1/2 cup/120 ml dry white wine
10-oz/280-g bag fresh or frozen green peas
1 cup/100 g Parmigiano-Reggiano cheese
Finely chopped fresh basil for serving
For the tarka
2 tbsp unsalted butter
2 tbsp extra-virgin olive oil
1 tbsp finely chopped fresh basil
1 tsp finely chopped fresh rosemary
1 tsp finely chopped fresh thyme
1/4 tsp freshly ground black pepper
1/8 tsp red pepper flakes
Snap off the tough ends of the asparagus and add them to a large soup pot. Slice the trimmed asparagus spears on the diagonal into 1-inch/2.5-cm lengths, leave the tips whole, and place both in a medium bowl and set aside.
Pour 12 cups/2.85 L water over the asparagus ends and add 1 tsp of the salt and the Parmigiano-Reggiano rind (if using). Bring the liquid to a boil over medium-high heat, reduce the heat to medium-low, cover, and gently simmer until the broth is fragrant, about 25 minutes. Strain the broth into a clean pot, cover to keep the broth warm, and discard asparagus stems. (The broth can be made up to a week in advance; reheat before making the risotto.) You should have about 10 cups/2.35 L of broth.
Melt the butter in a large heavy-bottomed pot over medium-high heat. Add the pepper and cook, stirring often, until fragrant, about 30 seconds. Stir in the onions and 1/2 tsp salt and cook, stirring often, until they are translucent and soft, 1 1/2 to 2 minutes. Add the rice and cook, stirring often, until the grains are opaque, 1 1/2 to 2 minutes. Pour in the wine and cook, stirring often, until it is absorbed, 1 to 2 minutes. Reduce the heat to medium and add 1 cup broth. Cook the risotto, stirring constantly, until the liquid is mostly absorbed (when you push a wooden spoon through the center of the pot, a trail should remain for 1 second before the rice comes back together), and then add another cup of warm broth. The rice will probably need about 2 minutes of cooking and stirring between each addition.
Meanwhile, make the tarka. Melt the butter in a medium frying pan over medium heat. Add the olive oil, basil, rosemary, thyme, black pepper, and red pepper. Cook, stirring often, until the mixture is fragrant, about 1 minute. Turn off the heat and set aside.
Once you have added 5 cups/1.18 L broth total to the risotto (after about 10 minutes), add the sliced asparagus, peas, and the remaining 1/2 tsp salt. You know the risotto is done when the rice is creamy, not mushy, the grains are plump yet separate, and the rice is cooked to an al dente doneness (there should be an opaque speck in the center of a grain of rice), after another 3 to 5 additions of broth and 8 to 10 more minutes. Turn off the heat. Add the tarka and the Parmigiano-Reggiano, stirring to combine. Spoon the risotto into serving bowls, shower with some fresh basil, and serve.