This rich and flavorful sauce is traditionally an accompaniment for steak, but it’s also a wonderful break from sour cream on a perfectly baked potato—so satisfying it can be the entire meal! Note: Most béarnaise sauce recipes call for making it in a double boiler to avoid curdling the yolks from direct heat—two inches of water are kept at a simmer in the bottom pan while you whisk the ingredients in the top one. However, if you use a low heat and whisk constantly, you can make the sauce in a small saucepan over direct heat.
For the potatoes:
- 4 large russet potatoes
- 1-2 tablespoons extra virgin olive oil, as needed
- A few pinches of coarse salt and twists of freshly ground black pepper
For the béarnaise sauce:
- 1/4 cup sherry vinegar
- 1 shallot, peeled and minced
- 1/2 teaspoon freshly ground black pepper
- 1 tablespoon fresh French tarragon leaves, chopped, or 1 teaspoon dried tarragon, crumbled
- 6 tablespoons unsalted butter
- 6 tablespoons extra virgin olive oil
- 2 egg yolks
- 1 tablespoon water
To bake the potatoes, preheat your oven to 450°F. Line a rimmed baking sheet with a large piece of parchment paper. Scrub and pat dry the potatoes, then place them on the parchment. With the tip of a sharp paring knife, pierce the potatoes on all sides. Rub them all over with olive oil and sprinkle them with salt and pepper. Bake until the tip of the knife easily goes through them, about an hour.
About 20 minutes before the potatoes are ready, make the sauce. Place the vinegar, shallots, tarragon, and black pepper in a small saucepan and bring to a boil. Lower the heat and cook until the vinegar is reduced by half. Take the pan off the heat and let the vinegar cool to room temperature, 10 to 15 minutes.
Melt the butter and set aside. Whisk the yolks and water into the vinegar reduction and place over low heat. Continue whisking until the mixture thickens and nearly doubles in volume. Then slowly whisk in the butter, about 2 tablespoons at a time; repeat with the olive oil. Continue whisking vigorously until the sauce thickens but is still pourable. If necessary, the sauce can sit for 15 minutes or so; whisk gently before serving as needed.
Plate the potatoes and make a large slash lengthwise in each. Top with dollops of the béarnaise sauce and serve the rest on the side.
Yields 4 servings