Annabel Langbein returns again and again to this savory, Asian-accented dish. The key is selecting dense, thick fillets of the freshest fish, so they stay moist throughout cooking. More Healthy Fish Recipes
In a small skillet, toast the sesame seeds over moderate heat, stirring a few times until golden, 3 to 4 minutes. In a small bowl, mix the soy sauce with the rice vinegar, mirin, grapeseed and sesame oils, scallions and ginger. In a large, shallow dish, brush the halibut fillets with half of the soy-ginger dressing. Cover and refrigerate for 30 minutes.
Preheat the oven to 450°. Transfer the halibut to a large, rimmed baking sheet and season with pepper. Bake the fish in the upper third of the oven for 10 to 12 minutes, or until glazed and just cooked through.
Spoon the rice into shallow bowls. Set the halibut fillets on top and spoon the spinach alongside. Pour the remaining dressing over the fish, sprinkle with the toasted sesame seeds and serve.
The dressing can be refrigerated overnight. The halibut can marinate for up to 3 hours.
New Zealand's famed Sauvignon Blanc has a gooseberry tanginess that's a great complement to the delicate, faintly sweet dressing here.