Rinse the tofu noodles under running water.
Julienne the onion and scallion.
Add perilla oil to a pan and sauté the onion over medium-low heat.
Add the tofu noodles and stir-fry for 2-3 minutes.
Season with soy sauce and a pinch of salt.
Transfer to a bowl and top with scallions and sesame seeds to finish.