In a heatproof bowl, combine the Gochugaru, sesame seeds, spring onion, and garlic.
Heat 2–3 tbsp vegetable oil over medium-high heat until it shimmers, then carefully pour the hot oil over the spice mixture.
Add the soy sauce and white vinegar into the bowl and stir well to combine.
In a separate bowl,mix the peanut sesame paste with water until smooth. Adjust the water slightly if you prefer a thinner or thicker sauce.
Combine the peanut sesame paste mixture with the spice mixture and stir until evenly blended.
Cook the noodles according to the package instructions until al dente. Immediately rinse them under ice-cold water to stop the cooking process, then drain well.
Place the noodles into a serving bowl, pour over the sauce, and toss to coat evenly.
Top with cucumber strips and a sprinkle of sesame seeds. Serve and enjoy!