Béarnaise Sauce

Step 1: Place the infused vinegar ingredients in a small saucepan over medium-low heat.

Step 2: Simmer for 2 minutes, then remove from the stove and let stand for 5 minutes to infuse.

Step 3: Strain, pressing to extract as much liquid as possible. You should have around 1 tablespoon of liquid. Cool for 5 minutes before use.

Step 4: Place the butter in a jug and microwave until melted, 1 to 1½ minutes on high. Watch it carefully so it doesn’t explode.

Step 5: Let stand for 30 seconds until the milky solids settle at the bottom and the clarified butter, the golden part, sits above them.

Step 6: Pour off 175 g / ¾ cup of the clarified butter and discard the remaining milky solids. Use the clarified butter while hot.

Step 7: Alternatively, melt 175 g / ¾ cup ghee, which is the same as clarified butter.

Step 8: Place the egg yolks, infused vinegar and salt in a tall, narrow container that the stick blender fits into all the way to the base. Blend briefly to combine.

Step 9: With the stick blender running on high, slowly drizzle in the butter over about a minute. The butter must still be hot; if it has cooled, reheat until hot.

Step 10: Once all the butter is added, blend for a further 10 seconds, moving the stick blender up and down.

Step 11: Add 1 tablespoon water and blend to incorporate. Add more water as needed, 1 teaspoon at a time, until the sauce is thick but loose enough to ooze across and coat a steak.

Step 12: Stir in the tarragon and chervil.

Step 13: Use immediately, or keep warm until needed. A good thermos will keep the sauce warm for at least 1 hour. Serve warm or at room temperature.