Prepare an ice bath. Bring 3 cups water and 1 teaspoon salt to a boil in a medium, heavy-bottomed pot. Add the asparagus and peas and cook 2-3 minutes, or until bright green and crisp tender. Using a hand strainer or slotted spoon, transfer the veggies to the ice bath (don’t drain the pot). Drain the veggies and set aside.
Bring the pot of water back to a boil. Add 2 tablespoons of butter and the Arborio rice. Cook, stirring, until the water comes back to a boil. Reduce the heat to a simmer; cover and cook 15 minutes.
Meanwhile, put the olive oil, shallots, garlic and a pinch of salt and pepper in a small skillet. Cook over medium heat, stirring, until tender and fragrant, 2-3 minutes. Add the wine; bring to a boil and reduce by half. Set aside.
After 15 minutes, check to see if the rice is cooked. It should be tender but not mushy (it should still have a bit of a bite). It will look quite soupy at this point, but don’t worry! Add the remaining tablespoon of butter, the grated Parmesan cheese, the lemon zest and the shallot/garlic/wine mixture. Stir until everything comes together—the risotto should be creamy and fairly loose (if you prefer your risotto on the thicker side, simmer it for a few more minutes, uncovered; if it’s too thick, add some water to thin it out). Fold in the peas, asparagus and mint. Taste and season with salt and pepper. Serve warm. Do Ahead: The risotto is best served immediately, but it can be made up to an hour in advance. If you make it ahead of time, don’t add the mint. Leave the pot covered at room temperature. Reheat gently, adding water to loosen as needed, and stir in the mint before serving.