Black bean sauce can be found in specialty-food shops or in the Asian sections of many supermarkets. Brown bean sauce or bean sauce also will work.
To prepare bean sauce, combine first 4 ingredients in a small bowl; set aside.
To prepare stir-fry, heat vegetable oil in a large nonstick skillet over medium-high heat. Add sliced onion, and sauté 6 minutes or until golden brown. Remove onion from skillet; keep warm.
Heat sesame oil in skillet over medium-high heat. Add ginger, pepper, and garlic, and cook 1 minute. Add green onions, and sauté 2 minutes or until onions are soft. Add pork, and sauté 5 minutes. Add scallops, and sauté 3 minutes or until scallops are done.
Return the sliced onion to skillet, and stir in bean sauce. Cook 1 minute or until mixture is thoroughly heated. Place pork mixture in a large bowl. Add the pasta, and toss well. Stir in the chopped cilantro, peanuts, and vinegar.