Steak-Spinach Salad with Sour-Cream Potatoes Recipe | Say Mmm

Ingredients

• 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