• Combine soy sauce, lemon juice, cornstarch, and sugar. Stir to dissolve sugar; set aside. Heat sesame oil in a wok over high heat until hot. Add chili flakes and remove from heat. Allow oil to stand for 10 minutes or more.
• Combine minced garlic and white part of onion in a small dish. Return oil in wok to high heat. When hot, add garlic mix and stir 15 seconds. Add asparagus and stir-fry until crisp-tender, about 4 minutes. Stir soy mixture and drizzle over asparagus. Cook, stirring, about 1 minute longer. Transfer to platter; sprinkle with sesame seeds and green onion tops and serve.
• Serves 8 as a side dish or 4 as a vegetarian topping over rice. Stir any leftovers with leftover rice and cooked egg to make fried rice.