What makes this keto bearnaise steak sauce so good is that it is not only creamy and tasty but also perfect for adding extra fat and flavor to steak; it's very easy to make at home and delicious.
Place a small saucepan over medium heat, add the 1/4 cup white wine vinegar, 1/4 cup white wine, 6 peppercorns, and 1 tablespoon onion. Reduce until 2-3 tablespoons of liquid remain.
1/4 cup white wine vinegar, 1/4 cup white wine, 6 peppercorns, 1 tablespoon onion
Strain out the onion and peppercorns and pour the liquid into a heatproof bowl. Add the 3 egg yolks.
3 egg yolks
Melt the 9 ounces unsalted butter until the milk fat (white liquid) has separated from the yellow butter. Set aside.
9 ounces unsalted butter
Place the bowl over a saucepan of simmering water and start whisking.
Remove the bowl from the heat and slowly pour in the hot butter while whisking, ensuring that the milk fat is left behind. This step is similar to making mayonnaise - if you add the butter too quickly the sauce will split.
Whisk in the 1/2 teaspoon salt, 1/4 teaspoon pepper, and 2 tablespoons fresh tarragon.