This sauce is an ode to the classic French dish of leeks in vinaigrette, swapping out the leeks for tender charred scallions. It acts as a bright, addictive condiment for this quick-cooking cut of steak. If you can’t find hanger steak, skirt steak works for this recipe—adjust cook time accordingly. The sauce also pairs well with roast chicken, pork chops...we could do this all day.
- ½ cup crushed or coarsely chopped walnuts
- 9 Tbsp. extra-virgin olive oil, divided
- 1 1½-lb. hanger steak, cut into 4 pieces, center membrane removed
- Kosher salt, freshly ground pepper
- ¾ tsp. Aleppo-style pepper, plus more for serving
- 5 tsp. sherry vinegar or red wine vinegar
- 1 Tbsp. chopped cornichons
- 1 Tbsp. chopped drained capers
- 1 Tbsp. whole grain mustard
Preheat oven to 350°. Toast walnuts on a rimmed baking sheet, tossing once, until golden brown, 8–10 minutes. Transfer to a medium bowl. Finely grate garlic over warm walnuts and toss with 6 Tbsp. oil.
Heat a large cast-iron skillet over medium-high. Season steaks with kosher salt and black pepper; sprinkle all over with Aleppo-style pepper. Rub with 2 Tbsp. oil and cook, turning occasionally, until deeply browned and an instant-read thermometer inserted into the thickest part registers 130° for medium-rare, 10–12 minutes. Transfer steaks to a cutting board.
Wipe out skillet and reduce heat to medium. Place scallions and 1 Tbsp. oil in skillet, season with kosher salt, and cook, turning occasionally, until softened and deeply charred, about 4 minutes. Transfer to cutting board; trim and cut into 1" pieces. Add to bowl with walnut mixture along with vinegar, cornichons, capers, mustard, thyme, and sugar and toss to combine; season with kosher salt and black pepper.
Slice steak against the grain and sprinkle with sea salt. Serve with scallion sauce and more Aleppo-style pepper.