Sandre au beurre blanc, Nantais-style pike-perch with butter sauce
Sandre au beurre blanc brings together two Loire-facing traditions: freshwater pike-perch and the sharp, butter-rich sauce associated with the Nantes area. The fish is kept simple so the sauce remains legible. Four boneless portions are pan-cooked until the skin is crisp and the flesh reaches 63 °C, then served with a beurre blanc built from shallot, dry white wine, wine vinegar and cold butter.
The sauce depends on reduction before enrichment. Wine, vinegar and shallot are simmered until only about 30 ml of syrupy liquid remains; that concentrated acid base is what allows a large amount of cold butter to be whisked in without turning the dish into a cream sauce. Add the butter gradually over very low heat, moving the pan off the heat whenever necessary. A glossy, opaque sauce with no free butter on the surface is the useful endpoint.
Cook the fish only after the beurre blanc is close to ready because this emulsion is at its best straight away. Pat the sandre dry, check carefully for pin bones, and start skin-side down so the skin can crisp while the flesh stays moist. The complete sauce is allocated across the four portions, so it is intentionally generous; serve immediately rather than holding the emulsion over strong heat.


