In a large bowl, spread out the slices of radishes. Season them with salt and pepper then drizzle with the olive oil. Either using a microplane, or using a vegetable peeler to remove strips of peel and mincing them with your knife, remove the zest from the lime and scatter it over the radishes. Cut the lime in half and squeeze its juice over the slices too. Toss the radishes to evenly coat with the dressing.