1 Place the onion, 1? tbsp tarra-
gon leaves with stems, vinegar,
wine, pepper and water into a
small saucepan and simmer until
the liquid has reduced to 1.5 tbsp.
2 Strain the liquid into a glass
bowl over a saucepan half-filled
with simmering water; add egg
yolks. Whisk until thick and foamy.
3 Whisk in the butter block by
block until it has all been incor-
porated and you have a bowl of
thick, creamy sauce.
4 Season and add the lemon
juice to taste. Just before serving,
stir in the remaining tarragon. To
keep warm, place the bowl over
another filled with warm water,
with the bottom of the Béarnaise
bowl submerged in the water.
Whisk thoroughly before serving.