Heat oil in a wok or large skillet over medium-high heat.
Add shallots and garlic, cook for 1 minute, or until they start to color.
Add chicken and stir fry until light golden, about 4 minutes.
Add lemongrass, chile (if using), stock, fish sauce, lie juice, and sugar. Bring to a boil. Reduce heat to low, cover, and simmer for 10 minutes. Add red pepper and cook for 5 minutes, or until chicken is cooked through.