1. Preheat oven to 400 degrees. Pat beef dry and season all over with salt and pepper. Heat a large saute pan over medium-high. Swirl in oil. Cook beef until browned on all sides, about 2 minutes a side. Transfer to a plate; let cool completely.

2. Line 2 baking sheets with parchment. Using a mandoline, slice potatoes into scant 1/8-inch-thick rounds. Brush parchment on one sheet with clarified butter. Working from outside in, arrange potatoes in overlapping lines to form a rectangle of same length as beef and wide enough to wrap around entire tenderloin. Brush entire surface of potatoes with remaining clarified butter; season with salt. Bake just until softened, 18 to 20 minutes. Remove from oven; press potatoes down and together with a spatula. Let cool completely.

3. Place beef atop potatoes on one long side of rectangle. Evenly spread pate over top and sides of beef. Using parchment, lift potatoes up and over meat to cover completely. Transfer, seam-side down, to other prepared baking sheet.

4. Bake 30 minutes. Increase heat to 425 degrees; bake until potatoes are golden brown on edges and a thermometer inserted in thickest part of meat registers 125 degrees, about 10 minutes more. Let rest on sheet 10 to 15 minutes.

5. Using 2 wide spatulas, loosen potatoes under beef from baking sheet; transfer wrapped beef to a cutting board. Use kitchen shears to cut through potatoes, then slice meat with a sharp knife; serve immediately.