4 oz. bacon, cut into 1/2-inch pieces
8 oz. Yukon gold or fingerling potatoes, cut into 1/2-inch pieces
kosher salt and black pepper
2 tsp. canola oil
1 ½ lb. sirloin steak (1 inch thick)
¾ C. crumbled blue cheese, such as Stilton or Roquefort (3 oz.)
¼ C. sour cream
¼ C. buttermilk
1 tsp. red wine vinegar
1 scallion, chopped
1 head romaine lettuce, torn into bite-size pieces (about 8 C.)

Cook the bacon in a large skillet over medium heat, stirring occasionally, until crisp, 5 to 7 minutes. Using a slotted spoon, transfer to a paper towel-lined plate. Reserve the skillet.
Add the potatoes to the drippings in the skillet, season with ¼ tsp. each salt and pepper, and increase heat to medium-high. Cook, tossing occasionally, until browned and tender, 12 to 15 minutes. Meanwhile, heat the oil in a second large skillet over medium-high heat. Season the steak with ¼ tsp. each salt and pepper and cook until and instant-read thermometer inserted in each piece register 130ºF, 5 to 7 minutes per side for medium-rare. Let rest at least 5 minutes before slicing. Mix together the blue cheese, sour cream, buttermilk, vinegar, scallion, and ¼ tsp. each salt and pepper in a small bowl. Divide the lettuce among plates, top with the steak, bacon, and potatoes, and drizzle with the dressing.