Tarragon Sauce

• 10 g butter
• a drop of olive oil
• 1 small onion

In a small saucepan, melt the butter with a drop of olive oil over a lowish heat, then gently fry the onion until it’s soft and translucent but not coloured. Add the wine and the lemon juice, raise the heat and boil until reduced down to a couple of tablespoons of liquid. Add the cream and the tarragon and boil again to reduce by a third. You can leave it as it is, slightly textured, or use a h