In a medium bowl, whisk together the Gochujang, soy sauce, brown sugar, honey, rice vinegar, minced garlic, sesame oil, grated ginger, and black pepper until the sugar has dissolved and the mixture is smooth.

Transfer the mixture to a small saucepan and simmer over low heat for 5 to 10 minutes, stirring occasionally. The sauce should thicken slightly and the flavors will become more concentrated.

Once the sauce reaches room temperature, remove off the heat and let it to continue thickening. Once cooled, if desired, garnish with sesame seeds and chopped green onions for an added touch of flavor and texture.