Bring a pot of water to a boil. Pulse the sesame seeds in a mini food processor with 2 tablespoons sesame oil, 1 tablespoon sugar and 1/4 teaspoon salt until powdery; set aside.
Prepare the stir-fry: Quarter, seed and finely dice the pickles and put in a bowl. In another bowl, mix the garlic, ginger, scallions, 1/2 teaspoon salt and the remaining 1/2 teaspoon sugar. Mix 1 tablespoon soy sauce and the broth in a third bowl. Mix the pork with 1 tablespoon soy sauce and 1/2 teaspoon salt in another bowl. Place the four bowls by the stove.
Place a large skillet over high heat. Add 2 tablespoons vegetable oil, then the pork, breaking it up with a wooden spoon, until cooked but not dry, 4 minutes. Transfer the meat to a bowl and toss with the remaining 1 tablespoon soy sauce.
Add the remaining 1 tablespoon vegetable oil to the skillet; stir-fry the pickles for 1 minute. Add the garlic mixture and fry 30 seconds. Add the broth and boil until reduced by half, 4 minutes. Divide the broth among bowls and drizzle with the chili oil and vinegar.
Meanwhile, add the noodles and bok choy to the boiling water and cook until just tender, 2 minutes. Drain and toss with the remaining 2 tablespoons sesame oil. Season with salt, then divide among the bowls. Top with pork and sprinkle with sesame powder. Serve with more sesame and chili oil.
Photograph by Sang An
Recipe courtesy Food Network Magazine