Cook the udon noodles according to the packaging's instructions. Transfer to a strainer and run cold water through the noodles to stop them from cooking. Set aside.
To make the sauce, in a small bowl, combine the low-sodium soy sauce, sweet soy sauce (kecap manis), and sesame oil and mix well. Set aside.
In a frying pan or a wok, heat 1 tbsp of canola oil over medium high heat. Cook the pork belly strips for about 2 minutes or until cooked. Add in the minced garlic, onions, and green onions and cook for another 2 minutes until the onions are softer. Add about 2 tablespoons of the sauce mixture and combine well. Turn the heat to high, add another tablespoon of canola oil into the pan and add in the cooked udon noodles (If the noodles stick together, run them through cold water until they are separated before adding them into the frying pan). Stir-fry for 1 minute, and add in the rest of the sauce mixture and combine well until all the noodles are equally coated with the sauce. Continue stir-frying for another 1 to 2 minutes to get a little bit of charring on the noodles. Remove from heat and transfer to a serving plate.
Top with white sesame seeds or more green onions.