Cook the Vegetables
Reduce the heat to medium and add the remaining 1 tablespoon butter to the skillet, then stir in the shallot and cook until lightly golden, 2 to 3 minutes. Add the peas, radishes, remaining ½ teaspoon kosher salt, and a little more pepper, stirring everything to coat with the pan juices. Stir in ¼ cup water, scraping up any browned bits from the bottom of the skillet.
Tip: Scraping up browned bits (fond) adds a rich depth of flavor to the vegetable mixture.