Preheat oven to 400 degrees. Separate greens from radishes; wash both well. Slice radishes in half; toss with 1 tablespoon each oil and vinegar. Season with salt and pepper. Arrange in a single layer on a rimmed baking sheet, cut-side down. Roast until tender and golden, 25 to 30 minutes.
Meanwhile, heat remaining oil and vinegar and the garlic in a medium skillet over mediumhigh heat. Cook radish greens, tossing, just until wilted, about 1 minute. Season with salt and pepper. Serve with radishes.