Marinate the cod:
In a small bowl, mix the miso paste, mirin, soy sauce, honey, and sesame oil.
Coat the cod fillets in the marinade, cover, and pop in the fridge for at least 10 minutes (longer if you’ve got time).

Cook the cabbage:
Heat the butter in a large frying pan over a medium heat.
Add the onion and cook for 5 minutes until soft and golden.
Stir in the garlic, then the shredded cabbage. Cook for 2 minutes until just starting to wilt.
Pour in the stock, season with salt and pepper, then cover with a lid. Let it braise gently for 8–10 minutes until tender.
Finish with a squeeze of lemon juice.

Cook the cod:
Heat a non-stick frying pan over medium heat.
Wipe off any excess marinade from the cod (so it doesn’t burn) and fry skin-side down for 3–4 minutes until crisp.
Flip carefully and cook for another 2–3 minutes until just cooked through.

Serve up:
Divide the braised cabbage between warm plates, top with the miso cod, and spoon over any pan juices.