Gather all ingredients.

Stir soy sauce, brown sugar, garlic, rice wine vinegar, gochujang paste, black pepper or gochugara chili powder, ginger, and sesame oil together in a saucepan; bring to a boil.

Whisk cornstarch and water together in a small bowl until cornstarch dissolves. Whisk cornstarch mixture into the boiling soy sauce mixture.

Reduce heat to medium-low and cook, stirring constantly, until sauce is thickened, about 3 to 5 minutes.