Wash and dry all produce. Adjust rack to upper position and preheat oven to 425 degrees. Cut potatoes into 1/2-inch-thick wedges, like steak fries. Toss on a baking sheet with a large drizzle of oil, rosemary, salt, and pepper. Roast in oven until browned at edges and tender, about 30 minutes total (we’ll check on them after 20 minutes).

Trim woody bottom ends from asparagus. Halve and peel shallot, then thinly slice. Trim, then thinly slice scallions, separating greens and whites. Place 3 TBSP butter in a small bowl and stir in half the truffle zest and half the scallion greens (TIP: Use more zest for extra truffle flavor.) Set aside to allow butter to soften.

Pat steak dry with a paper towel. Season all over with plenty of salt and pepper. Heat a drizzle of oil in a large pan over medium-high heat (we used nonstick). Add steak and cook to desired doneness, 3-7 minutes per side. TIP: For an even color all over, after cooking the steak, briefly sear the sides as well by holding it with tongs inside the pan

About 10 minutes before potatoes are done, remove from oven and push toward one side of sheet. Place asparagus on other side and toss with a drizzle of olive oil. Scatter scallion whites over stalks and season with salt and pepper. Return sheet to oven and roast until asparagus is tender and potatoes are done, about 10 minutes.

Transfer steak to a cutting board or plate and let rest. Drain any excess grease from pan. Heat a drizzle of olive oil in same pan over medium heat. Add shallot and cook, tossing occasionally, until softened, about 1 minute. Pour in stock concentrate and 1/4 cup water. Season with salt and pepper. Bring to a simmer, then let reduce by half. Remove from heat and stir in 1 TBSP truffle butter (save the rest for the next step).

Divide steak between plates. (TIP: Slice first if desired.) Spoon sauce over evenly. Add potatoes and asparagus to same plates. Dollop remaining truffle butter (to taste) over steak and potatoes. Garnish with remaining scallion greens.