Steamed Cod With Ginger and Scallions

In a large skillet, combine vinegar, soy sauce, and ginger. Season both sides of cod with salt and pepper; place in skillet with vinegar mixture.
Bring to a boil; reduce heat to a gentle simmer. Cover and cook until fish is almost opaque throughout, 6-8 minutes.
Meanwhile, cut green parts of scallions into 3 inch lengths; thinly slice lengthwise. Scatter over fish; cook, covered, until fish is opaque throughout and scallions are just wilted, about 2 minutes.