Discard any yellow leaves and hollow or coarse stems from broccoli rabe.
Cut off top 5 inches of broccoli rabe and reserve remaining stems for another use.
In a large heavy skillet heat oil over moderately high heat until hot but not smoking and saute broccoli rabe, stirring occasionally, until crisp-tender, about 4 minutes.
Add water and cook, covered, 2 minutes, or until tender.
Remove skillet from heat and stir in vinegar and salt and pepper to taste.