Peel your potatoes and chop into chunks. Steam or boil until very tender. Drain well and let them sit in the pot for a minute so extra moisture evaporates. Mash until smooth, ensuring they are warm but not hot before adding starch.

Add salt to the mashed potatoes and start mixing in potato starch a bit at a time. Aim for a smooth, non-sticky dough that feels pliable. Dust a surface with starch, roll pieces of dough into ropes, and cut into strips or ribbons.

Bring a pot of salted water to a gentle boil. Drop in the noodles and cook until they float and turn slightly translucent, about 2 to 4 minutes depending on thickness. Transfer to a colander and rinse briefly with warm water.

In a skillet, warm the neutral oil. Add garlic and cook until fragrant, about 30 seconds. Stir in soy sauce, chili oil, rice vinegar, sugar or honey, and a splash of water. Toss the noodles into the sauce and stir gently. Finish with sliced green onions and sesame seeds.