Pork belly browned in the pot, onion and scallion softened in its fat, then simmered in dashi and finished with miso off the heat. A deeply savoury Japanese home soup — the bowl you want on a cold day.
Thinly slice the pork belly and julienne the onion. Cut the scallion greens into 1–2 inch lengths and slice the whites thin; the greens go in the pot, the whites are for garnish.
Set each ingredient out in its own bowl before the heat goes on — the cooking moves quickly from here.
Bring the water and dashi powder to a boil in a small pot, then take it off the heat and set aside.
Having the stock hot and ready means the soup never stalls when it goes in.
Heat the oil in a deep soup pot and lay the pork belly in a single layer. Cook, turning once, until lightly browned and some of the fat has rendered.
A single layer browns; a pile steams. Work in two batches if the pot is crowded.
Add the onion and stir; its moisture lifts the browned bits from the bottom of the pot. After a minute, add the scallion greens and keep stirring until the onion turns translucent and takes on a little colour.
Those browned bits are a lot of the soup's depth, so scrape them up as the onion softens.
Pour in the dashi and bring it to a boil, then turn down to medium-low and simmer for 10 minutes.
Skim off any foam that rises; it keeps the broth clean.
Ladle a few spoonfuls of the hot broth into a bowl with the miso and whisk until smooth. Turn off the heat under the pot, then stir the miso back in until it's fully combined.
Don't let it boil once the miso is in. High heat dulls its flavour.
Ladle into bowls and scatter over the sliced scallion whites. Eat it hot.