BRAISED LEEKS WITH LEMON

4 small or medium leeks, tough outer leaves discarded and leeks trimmed to about 7 inches long and cut lengthwise into quarters or eighths
2 tablespoons unsalted butter
1/4 cup chicken or vegetable broth
1 teaspoon freshly grated lemon zest 

In a shallow dish soak leeks in cold water to cover 15 minutes, rubbing occasionally to remove any grit. In a heavy skillet melt butter over moderate heat. lift leeks out of the water and with water still clinging to them add to skillet. Cook leeks, stirring occasionally, five minutes and add broth and zest. Braise leeks, covered, 5 minutes, or until very tender, and season with salt and pepper.