In a large skillet heat the butter over medium-high heat. Add the mushrooms in an even layer and sprinkle with the lemon zest. Cook them undisturbed until they brown – about 2 min, then toss them with ¼ teaspoon salt and ¾ teaspoon black pepper and continue to cook until the mushrooms become tender but not mushy – about 4 to 5 min.
Transfer to a serving dish and sprinkle with the chives. Best is to serve them warm.
