"I threw this together the morning of a cooking contest when my previous plan didn't work out. It turned out great: firm but not crunchy, a little salty and a little sweet but not overpowering. The sauce was just right. Even my 1-year-old ate some! I used ponzu sauce, which is a citrus-flavored soy sauce. I buy it at my local Asian grocery and use it often. Serve hot or cold, over brown rice or by itself. Splash on more ponzu sauce or seasoned vinegar as desired."
Heat oil in a large skillet over medium heat. Add onion; cook and stir until translucent, about 3 minutes. Add garlic; cook and stir until soft, about 2 minutes. Stir in broccoli rabe until coated with oil. Cook until leaves wilt, about 3 minutes. Cover and cook, about 2 minutes more.
Uncover skillet. Add ponzu sauce. Cover and continue cooking until stems are firm but no longer crunchy, 2 to 3 minutes. Stir in rice wine vinegar and remove from heat.