This is more like alchemy than a recipe; as you near the end of the cooking process, a sudden transformation takes place and what looked like a pan full of wet radishes becomes something rich, dark, and deeply flavorful.
Warm 1 T of butter in a cast iron pan while you slice or quarter lengthwise a bunch of radishes. Wash the greens and slice them, too, then set aside.
When the butter has melted, add 1 T maple syrup, stir, and then add the radishes. Mix and let them cook for a minute or two before pouring in 1/2 cup of water. Boost the heat to high and bring to a boil. Lower the heat but maintain a simmer for 5-6 minutes, then add the sliced greens.
When most of the water has been absorbed, stir in 2 T of miso and another 1 T butter. Continue to cook on medium-low until everything is dark and caramelized.