Position a rack in the center of the oven, set a 12-inch ovenproof skillet (preferably cast iron) on the rack, and heat the oven to 450°F.
Trim the radishes and then halve or quarter them lengthwise, depending on their size. Trim and discard the stems from the tops, wash the leaves thoroughly, and pat dry or dry in a salad spinner.
In a medium bowl, combine the honey, butter, vinegar, 1/2 tsp. salt, and 1/2 tsp. pepper. Add the radishes and toss until coated. Transfer to the hot skillet, spread in a single layer, and roast, stirring occasionally, until the radishes are crisp-tender, 15 to 20 minutes. Remove from the oven, add the radish leaves, and toss until the leaves are just wilted; serve.