Heat sesame oil in a large skillet over medium heat.

Combine pork, 1 teaspoon black pepper, cornstarch, and salt in a bowl. Add to hot oil and fry until browned, about 3 minutes. Add green beans.

Combine chicken stock, soy sauce, Worcestershire sauce, chile-garlic sauce, vinegar, garlic, and sugar in a bowl and whisk together. Add to pork and green bean mixture. Bring to a boil. Cook until slightly thickened, about 3 minutes. Reduce heat and simmer until green beans are tender, about 5 minutes more.