With briny capers, a handful of fresh herbs, chopped hard-cooked egg, olive oil, and red-winevinegar, this quick sauce brings French flavor to any simply prepared poached, steamed, roasted, or sauteed fish.
Stir together vinegar, mustard, oil, capers, and herbs. Top with egg; season with salt and pepper. Serve with poached, sauteed, steamed, roasted, or grilled fish.
You can make this up to three days ahead without the egg and refrigerate it in an airtight container; stir in egg before serving.