-
1
Combine the Saikyo miso, mirin, and sake in a bowl and stir to a smooth, spreadable paste. The consistency should coat the back of a spoon and hold its shape on the fish surface without running. Taste: the paste should be sweet-forward, mildly salty, and faintly alcoholic — if it tastes sharply salty, the miso is not true Saikyo.
-
2
Spread the marinade paste over all surfaces of each fillet in an even layer. Place in a non-reactive container, cover tightly, and refrigerate for 2 to 3 days. Less than 24 hours yields only superficial flavour penetration; beyond 3 days the salt content of even Saikyo miso will begin to cure the flesh, altering its texture.
-
3
Remove the fillets from the marinade. This is where the dish lives or dies: wipe the excess miso from each fillet using your fingers or a palette knife, leaving only a thin, even smear — enough to be visible on the surface but not opaque. A thick residual layer will burn to black before the fish is cooked through; too little will produce neither the caramelised lacquer nor the Maillard complexity that defines the dish.
-
4
Grill the fillets over moderate heat, skin side down first. The sugar content of Saikyo miso burns rapidly at high heat; maintain medium heat and watch the surface constantly. Grill until the surface has developed a deep amber, slightly mottled lacquer — the colour of dark caramel, not of burnt sugar. The lighter highlights and deeper low points are correct; any black areas indicate excess miso or excessive heat.
-
5
Turn the fillets once and finish the flesh side briefly. The fish is done when it flakes in large, fat flakes with the intramuscular fat visible between them — white and glossy. The flesh should feel rich and yielding under gentle pressure, not firm or chalky. A sweet, nutty, deeply savoury smell — fermented, then caramelised — will be present throughout the kitchen from the moment the miso contacts the heat.