BRAISED BABY BOK CHOY

1 cup chicken or veg broth
3 tablespoons unsalted butter
3/4 lb baby bok choy, trimmed
1/2 teaspoon Asian sesame oil 

Bring broth and butter to a simmer in a deep large heavy skillet. Arrange bok choy evenly in skillet and simmer, covered, until tender, about 5 minutes. Transfer bok choy with tongs to a serving dish and keep warm, covered. Boil broth mixture until reduced to about 1/4 cup, then stir in sesame oil and pepper to taste. Pour mixture over bok choy.