Wang Mandu (King Dumplings)

Preparation

1. Step 1

   Make the mandu wrappers: Add the warm water, sugar, oil and yeast to a liquid measuring cup and stir to dissolve. Set aside until lightly foamy on top, about 5 minutes. Add the flour and salt to a large mixing bowl, then, using chopsticks, stir in the yeast mixture until combined.

2. Step 2

   Using clean hands, knead the dough directly in the bowl until smooth and less sticky, 5 to 7 minutes. In other words, use the heel of your hand to push the dough away from you then pull it back onto itself, like you’re repeatedly folding it in half.

3. Step 3

   Cover the bowl with plastic wrap and let the dough proof in a warm place until doubled in size, 1½ to 2 hours.

4. Step 4

   Meanwhile, make the filling: Heat a large skillet over medium. Add the oil, followed by the mushrooms, onion and jalapeño. Season with salt and pepper. Cook, stirring occasionally, until softened, 5 to 7 minutes.

5. Step 5

   Scooch the vegetables to one side of the pan and add the beef in an even layer to the empty side of the pan, smashing it down for maximum contact with the pan. Cook the beef undisturbed to let it caramelize like a burger on a griddle, about 1 minute, then stir it into the vegetables, breaking it up. Cook the mixture, stirring occasionally, until the beef is no longer pink, 2 to 4 minutes. Stir in the gochugaru, then turn off the heat.

6. Step 6

   Stir in the soy sauce, Worcestershire sauce and sugar, then taste for seasoning, adding more salt and pepper until delicious. Transfer this hot mixture into a medium mixing bowl to cool slightly, then stir in the egg yolk.

7. Step 7

   Make the dipping sauce: In a small bowl, stir together the onion, jalapeño, vinegar, soy sauce, sugar and 1 tablespoon water and set aside until ready to eat.

8. Step 8

   When the dough is doubled in size, punch it down, then divide it into 9 equal pieces (about 70 grams each). To form a bun, on a clean surface roll one piece into a ball, then flatten it with your palm. Using a rolling pin, roll the dough piece into a round as thin as you can (around 5 to 6 inches in diameter), keeping the center slightly thicker than the edges. Add 2 tablespoons of the cooled beef filling to the center and bring the edges up and around the filling, one edge at a time, pinching as you go around until your bun is completely sealed. Repeat with the remaining dough and filling.

9. Step 9

   Fill a wok or wide-bottomed pan (large enough to fit your steamer) with 2 to 3 inches of water. Bring to a simmer, then adjust heat to medium-low. Line your steamer, either bamboo or metal, with parchment. Arrange the buns in the steamer, spacing about an inch apart, and steam them, covered, until the dough is soft, fluffy and bouncy to the touch, 20 to 25 minutes. You may need to steam them in batches, as they are large. Serve with the dipping sauce.