Start by heating the olive oil in a large skillet over medium heat. Add the finely chopped onion and sauté until it becomes soft and translucent, about 3-4 minutes, releasing a sweet aroma.
Add the arborio rice to the skillet and stir gently, letting each grain toast lightly for about 2 minutes until edges turn slightly translucent and you hear a faint crackling sound.
Pour in a ladle of the hot vegetable broth and stir gently. Allow the liquid to absorb into the rice, which should take about 2-3 minutes, creating a creamy base. Repeat this process, adding broth one ladleful at a time, stirring gently after each addition.
About halfway through cooking, when the rice is just beginning to become tender, stir in the fresh green peas. Thaw frozen peas quickly under hot water if using, then add and stir to incorporate.
Continue adding broth and stirring until the rice is creamy and tender but still has a slight bite, roughly 18-20 minutes in total. The mixture should look velvety, with peas vibrant and cooked through.
Remove the skillet from heat and stir in the grated Parmesan cheese and butter, mixing until melted and glossy. Add lemon zest if you like a bright, citrusy note. Taste and adjust seasoning with salt and pepper as needed.
Let the risotto rest for 1-2 minutes, then give it a gentle stir to recombine the creamy texture. Serve immediately, garnished with extra Parmesan and a twist of black pepper for a perfect springtime dish.
