Stir miso and mirin together in a small bowl until smooth. Set aside.
Blanch and prep nectarines: Prepare an ice bath and set aside. Bring a large saucepan of water to a boil. With a small paring knife, make a shallow X through the skin on the bottom (non-stem end) of each nectarine. Drop into boiling water for about 1 minute. With a large slotted spoon, transfer nectarines to ice bath. When cool, slip skin off, remove pits and slice into wedges.
Trim leeks to remove tough outer layers and the dark-green parts, and slice lengthwise. Rinse thoroughly to remove dirt from between the layers. Slice leeks crosswise into thin half-moons.
Heat a medium saucepan over low-medium heat. Add oil, and when oil is hot but not smoking, add leeks and stir to coat evenly. Cook, stirring occasionally, until leeks are translucent and have significantly softened (8–10 minutes).
Add nectarines and cook an additional 1–2 minutes, stirring to mix the nectarines and leeks but avoiding smashing the fruit. Remove from heat, add miso-mirin mixture and stir to coat evenly. Add a splash of rice vinegar. Before serving, taste and adjust seasoning with sea salt and additional rice vinegar, if needed.
Heat grill to medium-high. Coat fillets in oil, then season lightly with sea salt and ground black pepper. Oil grill grates. Add fish and cook, undisturbed, until fillets have attractive grill marks and release easily (3–4 minutes). Flip and cook an additional 3–4 minutes, until fish flakes easily.
To serve, plate a piece of grilled rockfish and top with a generous spoonful of compote. Sprinkle with chives.
I like to put the remaining compote in a small bowl to serve alongside the dish. It’s a great way to liven up cooked grains and sturdy salads.
About this recipe
Rockfish may also be labeled as black bass, black rock cod, black snapper or sea bass. How it’s caught matters: Look for handline-caught rockfish.