- Prep Time
- 1 tablespoon extra-virgin olive oil
- 2 cloves garlic, smashed and peeled
- 2 ounces shiitake mushrooms caps, finely chopped
- 1 stick (4 ounces) unsalted butter
- 1 large egg yolk
- 1 tablespoon rice vinegar
- 1 1/2 teaspoons finely chopped fresh tarragon
- Salt and pepper
- 4 1 1/2 inches thick filet mignon steaks (about 8 ounces each)
Preheat the grill to medium-high. In a medium saucepan, heat the olive oil over medium heat. Add the shallot and cook until softened. Add the mushrooms and cook, stirring, until softened, about 5 minutes. Transfer to a medium, stainless steel bowl. Add the butter and 1/2 cup water to the saucepan and bring to a boil; transfer to a measuring cup. Wipe out the saucepan and add enough water to reach a depth of 1 inch. Bring the water to a simmer over medium heat.
In a blender, combine the egg yolk and vinegar. With the machine on, gradually add the hot butter mixture and blend at high speed until thick and pale, 30 seconds; add to the mushroom mixture. Sit the bowl over the simmering water in the saucepan and whisk the mixture until thickened and fluffy, about 5 minutes. Stir in the tarragon and season with salt and pepper.
Season the steaks with salt and place on the grill. Cover and cook for 7 minutes on each side for medium-rare. Serve with the sauce.