1-First Step: Gather and prep Measure all ingredients and have them within reach. Thinly slice 1 small shallot and finely chop fresh tarragon for the final finish. Separate 3 egg yolks and place them into the blender container. Clarify butter into a saucepan or melt it in a microwave-safe dish until very hot. Using hot butter is important for a successful emulsion.

2-Second Step: Make the infused vinegar Combine 1/4 cup dry white wine, 1/4 cup white wine vinegar, sliced shallot, and 1 tablespoon tarragon leaves in a small saucepan over medium-high heat. Bring to a boil, then immediately reduce heat and simmer. Let the mixture reduce until it measures about 1 1/2 tablespoons, which usually takes 5 to 7 minutes. The goal is a concentrated, aromatic liquid without burning the shallots. Strain the reduction through a fine-mesh sieve into a small bowl, pressing on the solids with the back of a spoon to extract all the flavor. Discard solids and let the infused vinegar cool about 5 minutes so it is warm but not scalding.

3-Third Step: Prepare the butter Melt 1/2 cup unsalted butter or ghee until very hot. You can microwave it covered for about 1 minute or melt gently on the stovetop. If using clarified butter, skim off the foam so you have clear hot liquid fat. Leave the melted butter in a measuring cup with a spout so you can drizzle it slowly during emulsification.

4-Fourth Step: Start the emulsion in the blender In a high-powered blender, combine the 3 egg yolks, the warm infused vinegar, 1 teaspoon lemon juice, and 1/4 teaspoon salt. Blend for about 5 seconds to combine and slightly warm the yolks. With the blender running on medium-high speed, very slowly stream the hot melted butter into the center of the blender. Go gradually this can take 30 seconds to a minute. The hot butter cooks and thickens the yolks while the blender forms a smooth emulsion. If the sauce seems too thick, add a teaspoon or two of warm water and blend briefly to loosen.

5-Fifth Step: Finish and season Stop the blender and transfer the sauce to a bowl. Stir in 2 teaspoons finely chopped tarragon leaves. Taste and adjust salt and lemon if needed. The final sauce should be glossy, velvety, and coat the back of a spoon.

6-Final Step: Serve and timing notes Serve warm immediately over grilled steak, poached eggs, steamed asparagus, or roasted fish. If making ahead, chill in an airtight container up to 2 days and reheat gently in 10-second microwave bursts or over a double boiler, whisking in a teaspoon of melted butter and warm water per 1/2 cup sauce to re-emulsify.