Heat the olive oil in a stainless steel wok or 12-inch skillet. Stir fry the onion and asparagus in wok for about 3 minutes over medium high heat, stirring constantly. Add ginger, garlic, chicken, and continue to stir-fry for another 5 minutes, stirring constantly. Add soy sauce, vinegar, and red chili flakes. Stir together and cover. Cook for another 2 to 3 minutes. This may have to cook for an extra couple minutes if the asparagus is thick. Season with sea salt and pepper to taste. Serves 4.