We made ours with a delicious spicy oil made with the sachet from some Buldak noodles (save the rest to have with a bowl of ramen stock) and it was so easy, and so delicious, that I have no idea why we don't use this delicious umami-rich sachet to spice up our lives more often.
Add the pieces of diced potato to a saucepan and cover with cold water along with a teaspoon of salt and bring to a gentle simmer until completely soft and beginning to fall apart.
Remove from the water with a collander and push through a ricer until super smooth. Allow to steam for a few minutes then work in the potato starch, kneading and folding until you have a really smooth dough. You may need to add more water or more flour to make the dough less dry or sticky - use your intuition! Divide this into roughly 25g balls, rolling them between your cupped palms to smooth them out. Use a chopstick to poke a hole in each one. This helps them cook quickly and gives the sauce somewhere to pool.
Heat a medium saucepan full of water to a rolling boil and tip in the potato balls. Simmer them for roughly 10 mins or until cooked through - they will rise to the surface and swell when done, but give one a test to make sure. They should have a mochi-esque texture.
Whisk the oil into the contents of the flavour sachets. Toss through the drained noodle balls and the sliced spring onion greens, along with whatever other condiments tickle your fancy.