Ingredients

• 1/4 cup sesame seeds, toasted and cooled completely
• 1 bunch scallions, trimmed and finely chopped
• 6 garlic cloves, minced
• 1/2 cup soy sauce
• 1/4 cup packed light brown sugar
• 3 tablespoons gochujang (Korean hot-pepper paste)
• 1 tablespoon Asian sesame oil
• 6 pounds beef short ribs or flanken
• 3 cups water
• 1 (2-inch) piece peeled fresh ginger, smashed
• Special equipment: an electric coffee/spice grinder
• Accompaniment: kimchi

Instructions

1. Grind sesame seeds to a coarse powder in grinder. Reserve 1/4 cup scallion greens, then whisk together remaining scallions, garlic, soy sauce, brown sugar, hot-pepper paste, sesame oil, and 2 tablespoons sesame-seed powder in a large bowl. Reserve remaining sesame-seed powder for serving. Add short ribs to soy sauce mixture, rubbing mixture into them. Transfer ribs to a large sealable plastic bag and seal bag, pressing out excess air. Marinate, chilled, at least 8 hours.
2. Transfer ribs to a wide 6- to 8-quart heavy pot and add water and ginger. Simmer, tightly covered, until ribs are very tender, about 3 hours.
3. Transfer ribs to a platter using tongs and keep warm, covered with foil. Skim fat from sauce and pour sauce through a sieve lined with a dampened paper towel into a bowl, then discard solids. Serve ribs with sauce in shallow bowls and sprinkle with reserved scallion greens and remaining sesame-seed powder.