Add the soy sauce, vinegar, water, onion, chilli pepper, sesame seeds and spring onion.
Add potatoes and water into a blender or food processor. Pulse or blend until smooth
Pour and strain the blended potato through a cheesecloth or nut milk bag and into a small bowl.
Place the potato solids in the cloth aside and allow the water to settle in the bowl for around 5 - 10 minutes. This will separate the water from the potato starch, which will sink to the bottom.
Slowly drain off the yellowish water, reserving the white potato starch layer at the bottom. Add the potato back in from the cloth and mix back together with the starch until well combined.
Add in the sliced long green chilli, onion, salt and pepper and mix again.
Heat vegetable oil in a large frying pan over a medium high heat. Spoon out and shape potato pancakes on the pan with a spoon. Optional: For extra crispy edges, add a little more oil to the pan and move it around, making sure to touch the edges.
Flip after a few minutes until golden brown on both sides. Serve while hot alongside the dipping sauce, gyoza sauce or gochujang mayo.
