Bring a large pot of water to a boil. Salt it generously, as you would for pasta.
Pour the rice in a steady stream and stir once.
When the water returns to a boil, reduce the heat to a simmer and cook until the rice is tender but still has a slight bite, about 15 minutes.
Drain well.
While the rice cooks, place a saucepan over medium heat.
Add half the butter or oil.
Once the butter is melted or the oil is hot, add the peas.
Cook, shaking the pan occasionally, until they are bright green, hot, and tender, approximately 5 minutes. If using frozen peas, ensure they are defrosted first.
Add the drained rice to the saucepan with the peas.
Add the remaining butter or oil and stir gently to combine.
Cook for 1-2 minutes, until everything is heated through.
Taste and adjust the seasoning with salt and a generous amount of freshly ground black pepper.
Serve immediately.
Add a splash of dry white wine or a squeeze of fresh lemon juice to the peas as they cook to brighten up the flavor.
Fold in 1/4 cup (960 ml) of freshly grated Parmesan cheese at the very end for a rich, savory finish.
