1. Preheat oven to 375°F. Slice baguette into 1/2-inch rounds, brush with olive oil, and bake until crisp, flipping once. Set aside.

2. Pat the beef tenderloin dry, season with salt and pepper. Sear in hot olive oil for 3–4 minutes per side. Let rest, then slice thinly.

3. In a saucepan, simmer white wine vinegar with shallots and tarragon until reduced by half. Strain if preferred.

4. In a double boiler, whisk egg yolks with the reduction. Slowly whisk in melted butter until creamy. Season and keep warm.

5. Top each crostini with a slice of beef and a spoonful of sauce. Garnish with chives and black pepper.

6. Serve immediately while the sauce is warm and the crostini are crisp.