Nanban-Zuke Southern Barbarian Vinegar Marinade Fish

Ingredients

• 800 g aji (horse mackerel), sardine, or smelt — small whole fish, cleaned and gutted; scored lightly if larger than palm-sized
• For the marinade
• 240 ml dashi
• 120 ml rice vinegar
• 60 ml mirin
• 60 ml light soy sauce (usukuchi)
• 2 red chilli (togarashi), sliced into rounds; seeds retained for heat
• 10 g dried kombu, cut into short strips
• For the vegetables
• 1 medium onion, halved and thinly sliced along the grain
• 1 medium carrot, peeled and cut into fine julienne
• 2 stalks celery or spring onion, sliced thinly on the diagonal
• For frying
• 500 ml neutral oil, for deep-frying
• 60 g potato starch or plain flour, for dusting fish

Method

1. 1
   Combine the dashi, rice vinegar, mirin, light soy sauce, togarashi, and kombu in a saucepan. Bring to a gentle simmer over medium heat and hold for 2 minutes. The marinade should smell assertively sour — sharper and more forward than everyday tsuyu. Remove from the heat but keep hot.
2. 2
   Add the sliced onion, carrot, and celery or spring onion directly to the hot marinade. Stir to submerge. The vegetables will begin to wilt in the residual heat; they should soften at the edges while retaining a faint resistance at the centre. Set the marinade vessel aside.
3. 3
   Pat the fish completely dry. Dust lightly and evenly in potato starch or flour, shaking off any excess. Heat the oil to 170–175 °C. Fry the fish in uncrowded batches until the exterior is crisp and golden and the fish floats freely in the oil — 3 to 4 minutes for small whole fish. Remove and drain briefly.
4. 4
   This is where the dish lives or dies: transfer the fried fish immediately — while both fish and marinade are still hot — into the marinade vessel, ensuring every piece is submerged. The thermal gradient of hot marinade meeting the hot-fried surface drives rapid acid penetration through the oil-coated exterior; if the fish or the liquid is allowed to cool first, this penetration stalls and the balance of the finished dish is irreparably compromised.
5. 5
   Leave the vessel uncovered until it reaches room temperature, then cover and refrigerate. After a minimum of 2 hours — and ideally 6 to 8 — the vinegar will have fully penetrated the protein and the vegetables will have completed their wilting. The liquid at the bottom of the vessel will be the most concentrated and flavourful. To serve, arrange fish over the vegetables and spoon the pooled marinade liquid over at the table.