How to Make It
Bring a medium saucepan of salted water to a boil. Add the snow peas and cook until bright green and crisp-tender, about 1 minute. Drain and rinse under cold water. Pat dry and cut into 1-inch pieces.
In a large skillet, boil the stock over moderately high heat until reduced to 1/4 cup, about 5 minutes. Add the sugar snaps and cook until bright green, about 2 minutes. Add the snow peas, soy sauce, butter and water and cook over moderate heat, stirring, until the vegetables are glazed, about 2 minutes. Season with pepper. Off the heat, add the radishes. Transfer the vegetables to bowls along with any liquid in the skillet. Sprinkle with the horseradish and sea salt and serve right away.