Preparation

• Melt the butter in a 2-quart saucepan over medium heat and let stand for a few minutes off the heat. Don’t stir it—you want the milky solids to fall to the bottom and the clear yellow butterfat to float to the top. Skim off any milk solids still on the surface with a spoon. Pour the butterfat into a measuring cup, leaving the milky-watery layer behind. Keep warm.
• Fill a 3-quart saucepan with 1 inch of water and bring to a simmer over medium heat; then reduce the heat to low.
• Put the egg yolks, lemon juice, 1/4 tsp. salt, and 2 Tbs. water in a 2-quart stainless-steel bowl that will fit over the saucepan without touching the water. Put the bowl over the pan and whisk vigorously until the mixture is thick and frothy and the whisk leaves a trail in the mixture, 2 to 5 minutes. Scrape around the sides of the bowl with a silicone spatula from time to time so that the yolks don’t stick or overcook and curdle.
• Remove the bowl from the heat and whisk for another 30 seconds, letting the eggs cool down a bit.
• Lay a folded kitchen towel over a cool saucepan off the heat and nestle the bowl into the pan to hold the bowl steady. Slowly drizzle in the warm clarified butter, whisking constantly, until all the butter is added and the sauce is smooth and creamy. (If at any point the sauce breaks and looks curdled, stop adding the butter and see Hollandaise Troubleshooting, opposite).
• Whisk in the lemon zest and more salt and lemon juice to taste. Serve immediately or keep warm for up to 30 minutes (see Make-Ahead Tip, below).

Make Ahead Tips

This sauce is best served right after you make it, but it can hold for 30 minutes. To keep it warm, put the uncovered bowl of sauce over a saucepan of hot (not simmering) water off the heat. Whisk again before serving.

Noisette Melt the butter over medium-low heat and continue to cook until it has a nutty fragrance and the milk solids have fallen to the bottom and turned golden, about 7 minutes. Skim the surface but use the golden milk solids from the bottom. Continue with the hollandaise recipe. The subtle nutty notes of the brown-butter pair beautifully with sole or flounder.

Béarnaise Simmer 1/4 cup white wine vinegar and 2 Tbs. dry white wine with 2 Tbs. minced shallot and 2 sprigs of fresh tarragon until reduced to 1 Tbs. of liquid. Remove the tarragon sprigs. Continue with the hollandaise recipe, using the vinegar reduction instead of the lemon juice. Finish with 2Tbs. chopped fresh tarragon instead of the lemon zest. This is a classic served with a pan-seared filet mignon.

Maltaise Substitute 2 Tbs. blood orange juice for the lemon juice, and blood orange zest for the lemon zest. (You could also use regular oranges or tangerines.) Try it on fat spears of steamed or grilled asparagus.

Refrigerate leftover hollandaise in an airtight container for up to 3 days. You won’t be able to serve it as a warm sauce, but it makes a nice spread for panini, or you could mix it with a little smoked salmon or chopped ham and broil on crostini for a great hors d’oeuvre.