2 tablespoons white miso
2 tablespoons unsalted butter, softened, divided
Salt and pepper
4 green garlic, thinly sliced on the diagonal
2 pounds Japanese turnips with greens
¾ cup water
1 tablespoon mirin (Japanese sweet rice wine)
Stir together miso and 1 tablespoon butter.
Remove green tops of the turnips and coarsely chop the leaves, discarding turnip stems. Cut turnips in quarters, or in half if very small, and add to a 12-inch heavy skillet along with water, mirin, remaining tablespoon butter, and a pinch of salt and pepper. Bring to a boil over medium-high heat, and boil, covered, 10 minutes.
Add the sliced green garlic and greens by handfuls, turning and stirring with tongs and adding more as volume in skillet reduces. Cover and cook 1 minute. Uncover and continue boiling, stirring occasionally, until turnips are tender and liquid is reduced to a glaze, about 5 minutes.
Stir in miso butter mixture and cook 1 minute. Add more salt and pepper to taste.