Preheat the oven to 220C, fan-forced. Line an oven tray with baking paper. Cut the pork belly into 2cm-thick slices and put on the lined tray. Drizzle with 2 tsp oil and roast for 32-35 mins until just tender. Drain the excess oil from tray. Brush or spoon half the tonkatsu sauce over the pork. Roast for a further 5-8 mins until the pork is tender and caramelised.
Step 2 — Prep ingredients
Meanwhile, cut the white part of the spring onion into short batons and thinly slice the green stem. Shred the carrot using a julienne peeler or coarsely grate with a box grater. Quarter the pak choy lengthwise (see cooking tip).
Step 3 — Prep miso stock
Bring a small saucepan of water to the boil for the eggs. Put the miso, stock powder, 1 tbs soy sauce and 20g butter in a heatproof jug, add 1.25L (5 cups) boiling water and stir to dissolve.
Step 4 — Boil eggs
Cook 2 eggs in the pan of boiling water for 6 mins for soft-boiled, or 8 mins for hard-boiled. Drain, then cool in cold water. Peel and halve the eggs.
Step 5 — Make broth
While the eggs are cooking, heat 2 tsp oil in a large saucepan over high heat. Cook the spring onion batons and carrot, stirring occasionally, for 2-3 mins until softened and lightly charred. Stir in the miso stock and bring to a simmer.
Step 6 — Cook noodles and serve
Add the noodles and pak choy to the broth and cook for 3 mins or until the noodles and pak choy are tender. Stir the remaining tonkatsu sauce into the broth. Taste, then season with pepper. Divide the ramen, pork belly, egg and seaweed among bowls. Scatter over the sliced spring onion and a pinch of shichimi togarashi* to serve.