Clean and season a whole fish and let boil with 1 sliced onion, ½ cup of vinegar, a few slices of lemon and 2 sprigs of parsley. Add a tablespoonful of butter and let cook until tender. Remove the fish to a platter; mix the sauce with 1 tablespoonful of brown sugar, a pinch of ginger, cinnamon and nutmeg and the juice of a lemon. Let boil well; then thicken with the yolks of 2 beaten eggs and pour over the fish. Serve cold. Garnish with lemon-slices and olives.
A sweet-sour poached fish served chilled, of the sort found across Eastern Europe. The recipe assumes you know how much water to use and how to handle an egg-yolk liaison, so those are the two places to be careful.
- The hinge: the yolks must not boilOnce the eggs go in, the sauce cannot return to a boil or it will scramble into threads. Take the pan off the heat, temper the beaten yolks with a ladle of the hot liquid, stir them back in, and hold the pan over low heat only until it thickens enough to coat a spoon, around 160-170F.
- The missing liquidNo water is specified. Lay the fish in a pan just large enough to hold it and add enough water to barely cover, perhaps 3-4 cups for a 3 lb fish; the vinegar and aromatics season that liquid. Too much water and the finished sauce is thin and dull.
- Choosing the fishThe recipe names no species. Carp, pike or whitefish suit a dish of this kind, and their gelatin helps the sauce set lightly as it cools. A 2-3 lb whole fish serves four. Sea bass, trout or a small salmon work; delicate flatfish will fall apart.
- Poach, do not boilDespite the wording, keep the liquid at a bare shiver, 175-180F, with the surface just trembling. A rolling boil tears the skin and toughens the flesh. A whole 2-3 lb fish is done in roughly 20-25 minutes, when the flesh at the thickest point flakes and reads 145F.
- Reducing the sauceThe poaching liquid may be too weak and too sharp straight from the pan. Strain it, then boil it down with the sugar and spices before you thicken it; 'let boil well' at least implies a hard boil at this stage.
- Spice quantities"A pinch" of each of ginger, cinnamon and nutmeg is meant to be barely detectable behind the vinegar and lemon. About an eighth of a teaspoon of each is a reasonable reading; the dish should taste sour-sweet, not mulled.
- Serving coldChill the fish and sauce separately if you want a clean coating, or pour the sauce over while both are warm and refrigerate the platter so the sauce sets against the fish. Give it at least four hours. Garnish with lemon and olives only after it is cold.
Sweet-sour poached fish, served cold in its own thickened and lightly jellied liquid, belongs to the Jewish and Slavic kitchens of Eastern Europe, where carp and pike were plentiful and freshwater fish could be prepared in advance for a Sabbath when no cooking was done. The combination of vinegar, sugar, lemon and warm spices is generally traced to the medieval sweet-sour sauces of Central Europe, and closely related versions survive as Polish karp po żydowsku. That such a dish was labelled simply "Russian" is unsurprising in cookbooks of the early twentieth century, which were rarely fussy about which part of a very large empire a recipe came from.