Few people think of eating warm radishes, but they are delicious—like turnips with a little bite. According to Tony Maws, who describes himself as "more of a butter guy than an olive-oil guy," some butter also softens the edge.
In a large skillet, bring the vegetable stock and butter to a boil over moderate heat. Add the radishes and cook, stirring occasionally, until they are crisp-tender and the liquid has thickened slightly, about 15 minutes. Season with salt and pepper and transfer to a shallow bowl. Scatter the sorrel over the top and serve.
Save the radish greens for the Potato, Leek and Radish Green Vichyssoise.