Mix together gochujang, tomato sauce, soy sauce, sugar, garlic, gochugaru and sesame oil in a small bowl.
1 tbsp Korean hot pepper paste / gochujang, 1 tbsp tomato sauce / ketchup, 1/2 tbsp soy sauce, 1 tsp garlic, 1 tsp Korean hot pepper flakes / gochugaru, 1 tsp sesame oil, 1/2 tbsp sugar