Step 1Heat the peanut oil in a wok or large skillet over high heat. Add the ginger, garlic and green onions and cook, stirring, until very fragrant, about 30 seconds to 1 minute.
Step 2Stir in the tomato paste, chile bean sauce, black vinegar, sugar and sesame oil.
Step 3Mix together the chicken broth and cornstarch and set aside.
Step 4After about 2 minutes the mixture in the wok will look thick and somewhat sticky. Add the shrimp and crab and cook, stirring, until the shrimp have become pink and no longer translucent, about 2 to 3 minutes. Stir in the cornstarch mixture and the sauce will thicken almost immediately.
Step 5Serve over pan-fried noodles.