Clean the pork belly and let it drain. Marinate with 1 tablespoon fish sauce, 1 tablespoon seasoning salt, 1 tablespoon MSG, 1/2 teaspoon black pepper, 1 tablespoon sugar, 1 tablespoon caramel sauce, and 1/2 minced garlic clove. Place the meat in the refrigerator for 2 hours. Then, put small portions into the air fryer and set it to fry at 300°F for about 20 minutes. Every 5 minutes, open the fryer to flip the meat so it cooks evenly and doesn't burn on the edges.

Peel and thinly slice the kohlrabi and carrot. Toss them with a little salt and vinegar, then rinse. Boil 2 cups of water, add 1 tablespoon seasoning salt, 4 tablespoons fish sauce, 1 tablespoon MSG, 4 tablespoons sugar, 5 tablespoons vinegar, and 1/2 teaspoon black pepper. Stir well and let the mixture cool slightly. Add the kohlrabi, carrot (pickles), and minced garlic and chili to make the dipping sauce for the Bún chả.