Combine marinade ingredients in a bowl. Add chicken and stir to coat. Let stand for 10 minutes.
In a large pot of boiling water, cook noodles until tender, about 3 minutes. Drain, rinse with cold water and drain again.
Place a stir-fry pan over high heat until hot. Add oil, swirling to coat sides. Add garlic, chilies, and sugar; cook, stirring until garlic is fragrant and sugar begins to caramelize, about 15 seconds. Add chicken and stir-fry until surface of chicken turns white, about 1 minute. Add broth; cover and cook until chicken is no longer pink in centre, 3 to 4 minutes. Add green onions, fish sauce, and lemon juice; cook for 30 seconds. Remove pan from heat and stir in mint.
Place noodles on a serving plate and spoon chicken mixture over the top.