Heat the sesame oil in a small saucepan over medium heat. Add the kimchi, gochujang, and garlic. Cook and stir occasionally, until the gochujang is lightly toasted, 2 minutes or so.
Add the tomato sauce and sugar. Stir and cook until bringing to a simmer. Lower the heat and let the sauce simmer to thicken slightly, 3 minutes or so. Once done, transfer the sauce to a bowl to cool slightly before using.
Preheat the oven to 550 F (290 C).
Place the pizza crust on a large baking sheet. Spread 3 tablespoons of pizza sauce in a thin even layer on the pizza crust (*Footnote 2). Spread the kimchi evenly over it, and cover it with a layer of sliced (or shredded) cheese.
Place the baking sheet in the fully heated oven. Bake for 6 to 8 minutes, or until the crust turns golden brown and the cheese is fully melted.
Slice the pizza and enjoy!
