(Alternatively, you can roast the fish in a parchment-lined dish in a 400°F oven for 8 minutes per inch of thickness. You do not need the 2 tablespoons of oil or to flip the fillets, if roasting.) ...

The pickled onions as well as the dressing can be made in advance, and the fish needs to marinate for only about 20 minutes, all of which makes this recipe especially weeknight friendly.