Béarnaise sauce is a classic French accompaniment to some really good grilled meat or fish and it's really, really simple to do. It's got a beautiful creamy texture, you've got a little bit of acidity from the lemon juice and you've got that nice aniseed flavour from the tarragon. It partners amazingly and it's really easy to make so here we go.
Start by adding three egg yolks into a blender or a food processor along with a splash of water and whizz these together. OK, so on with the butter, we need to clarify this. This is 250g of butter, put the butter over a low heat. Take a second saucepan and add a teaspoon of lemon juice, two teaspoons of tarragon vinegar or white wine vinegar, some peppercorns and bring the whole thing to a boil.
OK, so we're ready to bring all these ingredients together but it's a really handy thing to have a few ice cubes just on the side just in case this gets too hot and it starts to curdle, you could add an ice cube and it'll hopefully bring all the mix back together.
So what we need to do know is to sieve the reduction and pulse. Add the melted butter whilst blending; it's really important to do this slowly to make sure you don't split the sauce. Continue to blend the mixture until the sauce thickens, then transfer your sauce to a serving bowl. Finely chop your fresh tarragon and sprinkle it over the sauce and stir through.
That's how you make a classic Béarnaise sauce.