Cook noodles according to package directions. Drain and set aside.
Using a whisk, combine sauce ingredients in a small bowl, then set aside.
Heat sesame oil in a large nonstick skillet over high heat. Add scallions and shrimp. Cook, stirring often, until scallions are bright green, 1 to 2 minutes.
Crack egg into the skillet and continue cooking, stirring constantly, until egg and shrimp are cooked through, about 1 minute.
Add noodles, sauce, and half of the peanuts. Toss well to combine.
Divide into four serving bowls, and top with fresh cilantro and remaining peanuts. This noodle bowl pairs well with a side of steamed broccoli.