Place the radishes in a large skillet and add just enough cold water to cover, about 2 1/2 cups. Add the butter, sugar, salt, and pepper and bring to a boil.
Reduce heat to medium-low and simmer until the radishes are tender when pricked with a paring knife and the liquid has reduced to a glaze, about 12 minutes.
If the radishes are tender but the liquid hasn't reduced sufficiently, use a slotted spoon to transfer them to a serving dish and continue reducing the liquid. Spoon it over the radishes and serve with buttered crusty bread.
I absolutely detest radishes, so when I received my weekly produce bushel which included radishes I looked up recipes to try and this one came up. I have so say they taste amazing! I love them!