In a small bowl, mix 1 tablespoon of cornstarch with 1 tablespoon of water until it's well combined and smooth. This will help thicken your sauce.
In a small saucepan, combine 1/2 cup of soy sauce, 1/4 cup of brown sugar, 2 tablespoons of rice vinegar, 1 tablespoon of gochujang, 1 tablespoon of sesame oil, 3 minced garlic cloves, and 1 teaspoon of grated ginger. Stir to combine all the ingredients.
Place the saucepan over medium heat. Stir the mixture occasionally until the sugar has dissolved and the sauce starts to bubble.
Once the sauce is bubbling, add the cornstarch-water mixture to the saucepan. Keep stirring for another 2-3 minutes until the sauce thickens to your desired consistency. Remove it from the heat.
Allow the sauce to cool before transferring it to a storage jar. It can be stored in the refrigerator for up to two weeks.