Dice ½ medium yellow onion (about 1 cup). Mince 3 garlic cloves.

Melt 3 tablespoons unsalted butter or heat 3 tablespoons olive oil in a large saucepan over medium heat until shimmering. Add the onion and ¼ teaspoon of the kosher salt and cook, stirring occasionally and reducing the heat as needed so the onions don’t burn, until very soft and light golden brown, about 10 minutes. Meanwhile, finely grate the zest of 1 medium lemon (about 1 ½ packed teaspoons), then juice half the lemon. If needed, finely grate 1 ½ ounces Parmesan cheese (about ¾ loosely packed cup), plus more for serving if desired.

Add the garlic and 12 ounces orzo to the pot and cook until fragrant and toasty-smelling, about 2 minutes. Add 1 box broth and the remaining ¾ teaspoon kosher salt, and scrape up any browned bits from the bottom of the pot with a wooden spoon. Bring to a boil over medium-high heat.

Reduce the heat to maintain a simmer and cook uncovered, stirring frequently to keep the orzo from sticking, until the orzo is tender and almost all of the liquid is absorbed, 10 to 12 minutes. If the orzo has absorbed all the liquid before it is ready, add water 2 tablespoons at a time as needed.

Remove from the heat. Add ¾ cup frozen peas and the Parmesan and stir until the peas are just heated through and the cheese is melted, about 1 minute. Stir in the lemon zest and 2 teaspoon of the lemon juice. Taste and season with more lemon juice and kosher salt as needed. Serve garnished with chopped parsley and more Parmesan cheese if desired.