Put the oven rack in the upper middle position, put a pizza stone (or baking sheet) on it and preheat to 475 degrees F.
To make the sauce, just mix the 1 tablespoon gochujang with enough kimchi juice so that it's thin enough to easily spread (but not watery). Add the ½ teaspoon toasted sesame oil and 1 clove garlic and stir to combine.
On a well floured surface, roll the 450 grams pizza dough out until it is less than ¼" thick. Dust a pizza peel (or wooden cutting board) with course ground cornmeal and lay the dough on top. I used a special pizza pan for my toaster oven so I made the pizza directly on the pan.
Use a spoon to spread the sauce on the dough.
Top the sauce with a thin layer of some of the 60 grams Gruyere cheese
Top with cheese with the sliced 100 grams pork belly and ½ cup kimchi
Top with the remaining cheese and 1 scallion
Gently transfer the pizza to the preheated pizza stone and bake until the crust is golden brown. Remove from oven, garnish with cilantro, slice and enjoy!