In a medium saucepan, combine the water, ketchup, sugar, cilantro, cornstarch, and seasonings. Bring to a boil, reduce the heat and simmer, uncovered, for 5 minutes. Cool for 10 minutes and blend in the peanut butter and green onions. Toss the sauce with the hot linguine and red cabbage. PRESENTATION: Garnish with green onion curls. Serve with a marinated cucumber salad.