- 2 medium russet potatoes
- 3 tablespoons olive oil, plus more for brushing
- 1/2 cup sour cream
- 2 tablespoons buttermilk
- 1/4 cup chopped fresh chives
- Juice of 1/2 lemon
- Kosher salt and freshly ground pepper
- 1 3/4-pound boneless sirloin steak
- 1 large red onion, sliced into thick rings
- 6 ounces baby spinach or chopped regular spinach
- 2 to 3 tablespoons steak sauce
Preheat the oven to 400 degrees F. Pierce the potatoes with a fork and brush with olive oil. Bake directly on the oven rack until tender, about 1 hour. Cool slightly, then cut into chunks. Mix the sour cream, buttermilk, chives and lemon juice in a large bowl and season with salt and pepper. Stir in the potatoes.
Meanwhile, preheat a grill to high. Brush the steak and onion rings with olive oil and season with salt and pepper. Grill the steak until marked on the bottom, about 7 minutes, then turn and cook 4 to 5 more minutes for medium-rare. Grill the onion rings until charred, about 2 minutes per side. Transfer the steak and onion rings to a cutting board and let rest 5 minutes.
Roughly chop the onion rings and toss with the spinach, steak sauce, 3 tablespoons olive oil, and salt and pepper to taste in a bowl. Thinly slice the steak. Divide the salad among plates, top with the steak and serve with the potatoes.
Photographs by Kate Sears