Poached Fish with Russian Sauce

“Russian Sauce” is probably the origin of Russian dressing, though the two no longer have much in common; still, the pickles and capers mark the relationship. This is most traditionally made with sturgeon (which is a wonderfully sturdy and flavorful fish) but can be made with any firm white fillet, from carp, catfish, or sturgeon to red snapper, sea bass, or grouper. Serve with boiled potatoes or plain white rice.