Place the mirin, soy sauce, sake and sugar in a small saucepan. Heat gently and mix until all the sugar has dissolved. Remove from the heat and whisk in the miso paste together with sesame oil until combined. Leave to cool to room temperature. Coat the cod with the marinade, cover with cling film and infuse overnight.
The next day, melt the butter in a pan over a medium heat. Add the carrots and ginger and cook for three to four minutes. Pour in the stock, reduce the heat and simmer for a further eight to 10 minutes. Once the carrots are cooked and the liquid has reduced by two-thirds, transfer the veggies and cooking liquor to a blender and purée. Once silky smooth, season to taste.
Season the kale with oil, salt and pepper, coating all the leaves. Spread onto a baking tray and roast for eight minutes at 160°C until crisp. Leave to cool.
Heat the oven to 200°C. Drain the chickpeas and rinse. Transfer to a kitchen towel and pat dry. Spread out onto a baking tray, season with a drizzle of oil, salt and paprika and roast for 25 minutes until crisp.
Ten minutes prior to the chickpeas being cooked, turn your attention to the skrei cod. Heat the oil in a non-stick pan over a high heat. Sear the cod for two minutes on each side, caramelising its exterior. Transfer to a baking tray and place in the oven for eight to 10 minutes until golden brown.
Serve on a drizzle of purée, delicately sprinkle the chickpeas and garnish with the crispy kale.