Slice chicken in half lengthwise to get thin pieces. Prick lightly using a fork or a knife to help tenderize.

Combine soy sauce, brown sugar, ginger, fish sauce, and lime juice in a large bowl, resealable plastic container, or large zip-top bag. Add chicken tenders, making sure marinade fully covers chicken. Cover and chill in the refrigerator for at least 2 hours.

Preheat an outdoor grill for high heat and lightly oil the grate. Remove chicken from marinade and thread onto metal skewers.

Meanwhile, add marinade to a small saucepan with cornstarch and bring to a boil. Boil until thickened, 3 to 4 minutes. Turn off heat and transfer sauce to a small bowl for dipping.

Grill skewers on the preheated grill until no longer pink in the centers, about 5 minutes per side. Garnish with scallion and serve with sauce on the side.