Total time: 25 minutes
In a small bowl, combine scallions, soy sauce, sugar, ginger, sesame oil and crushed red pepper flakes. Set aside. In a large saucepan, bring chicken stock to a boil. Add asparagus and simmer over medium-high heat until tender, about 2 minutes.
In a medium bowl, beat eggs. Slowly pour eggs into soup, whisking continuously to create egg threads. When cooked (about 20 seconds), turn off heat. Divide rice and chicken among 4 bowls. Ladle soup into bowls and pass reserved sauce at the table.