To a bowl, add ground beef, 1 tsp soy sauce, and ¼ tsp pepper. Very lightly mix together, then set aside.
Bring a large pot of water to a boil. Add enough salt to make it salty like broth, then add pasta. Cook 1-2 minutes less than what the box says, reserving ¼ cup pasta water. Drain and set aside.
In a large pan or wok, heat oil over high heat. When hot, add onion and ground beef mixture. Sauté for 3-4 minutes, stirring frequently, until no longer pink. Then add garlic, cooking for 30 more seconds until fragrant.
Add cooked pasta, tomato paste, remaining 1 tsp soy sauce, oyster sauce, frozen peas, and ¼ cup pasta water. Season lightly with salt and pepper. Stir continuously over high heat until pasta water is absorbed. Season to taste.
Garnish with sliced green onion.
