01 - Bring a pot of salted water to a boil. Blanch the asparagus pieces for 2 minutes, then add the peas and cook for 1 more minute. Drain and transfer immediately to a bowl of ice water. Drain again and set aside.
02 - In a large saucepan, melt 2 tablespoons of butter over medium heat. Add onion and cook until soft and translucent, about 3–4 minutes. Add garlic and cook for 1 minute more.
03 - Add the Arborio rice and stir for 1–2 minutes until the grains are well coated and slightly translucent at the edges.
04 - Pour in the white wine and cook, stirring, until nearly evaporated.
05 - Add one ladleful of warm vegetable broth and cook, stirring frequently, until most of the liquid is absorbed. Continue adding broth, one ladleful at a time, stirring often and allowing each addition to absorb before adding the next. This should take 18–20 minutes; the rice should be creamy and just tender.
06 - Stir in the blanched asparagus and peas; cook for 2–3 minutes until heated through.
07 - Remove from heat. Stir in the remaining tablespoon of butter, Parmesan cheese, parsley, and lemon zest. Season to taste with salt and pepper.
08 - Serve immediately, topped with extra Parmesan and a sprinkle of fresh herbs if desired.