I love this simple butter sauce, often known by its French name of beurre blanc; it makes an elegant accompaniment to fish, vegetables and egg dishes. Because this sauce does not contain any egg yolks it is more likely to separate than the other hot emulsified sauces, and it really should be made just before serving. It only takes a few minutes to make.
When adding the butter in step 2 be sure to whisk vigorously so it emulsifies before melting and becoming oily. If the sauce does separate, it cannot be rescued unlike the sauces that contain egg yolks, so you will have to start again. It is important to use unsalted butter. Makes about 300ml (½pint).
Boil 2–3 finely chopped shallots with 3tablespoons each white wine and white wine vinegar in a heavy-based saucepan until reduced to 1–2tablespoons and thick and syrupy. Add 1tablespoon double cream and boil again until reduced to 1–2tablespoons. (This step can be done ahead.) Adding the cream helps to stabilize the sauce before the butter is whisked in.
Over a low heat, whisk in 300g (10oz) diced chilled butter, little by little until incorporated. Increase the heat and bring just to the boil, whisking constantly and vigorously to stabilize the emulsion. You can either strain out the shallots or leave the sauce as it is. Season with salt and pepper to taste, using white pepper to avoid any black specks, and serve at once.
Rich hollandaise sauce is a traditional accompaniment for delicately poached salmon with fresh dill.