Whisk garlic, chiles, ginger, oil, soy sauce, vinegar, sugar, fish sauce, and salt in a medium bowl until sugar and salt dissolve.
Add lemon slices and thyme. Place marinade and chicken in a large resealable plastic bag. Turn to coat, and chill at least 12 hours, up to 24 hours.
Heat oven to 450°. Remove chicken from marinade, shaking off excess, and place, skin side up, on a rimmed baking sheet. Cook until chicken is cooked through, about 25–30 minutes.
Serve chicken with lemon wedges for squeezing over.