Let’s begin with the obvious, boiling the spaghetti in a pan. We trust your spaghetti boiling ability, but just in case, add 200g spaghetti to a pan of boiling water with a pinch of salt and boil until al dente (not mushy).
Next, cut your onion into small pieces and fry it with the natto in a frying pan. Once the onion is translucent and cooked and the natto is warm, add the drained boiled spaghetti with a knob of butter and continue frying and mixing.
Finally add the tsuyu stock and mix well before taking the pan off the heat. Garnish with nori sprinkles, and fujikko to serve and you’re done. You can even try cracking a raw egg over the top for extra taste and protein.