5 egg yolks
juice of 1 lemon
1/2 teaspoon cayenne
1 teaspoon salt
1 teaspoon sugar
4oz/1 stick unsalted butter, cut into tablespoon-size chunks
Place an inch of water in the pot, cover and bring to a boil.
Place the egg yolks in the metal bowl and whisk vigorously until they lighten in texture and colour. This is important, as it partially denatures the proteins in the yolks, which will prevent them from curled when faced with the lemon juice.
Add 2 teaspoons of the lemon juice, 1/4 teaspoon of the cayenne, a pinch of salt and all of the sugar. Whisk until smooth.
When the water boils, reduce the heat to medium low and place the bowl on top of the pot.
Whisk the egg mixture gently but continuously for about 7 minutes, or until it moves like very heavy cream (the whisk will leave a definite trail in the liquid).
Remove the bowl from the pot and set it on a dish towel (for stability).
Whisk the butter into the mixture 1 piece at a time, allowing each piece to melt almost completely before adding the next.
Taste, adjust seasoning, and serve immediately.
From "I'm Just Here for the Food" by Alton Brown