Grilled sirloin steak and onions with spinach and sour cream potatoes

Ingredients:

• 0.8 kg boneless sirloin steak
• 2 medium potatoes
• 3 tbsp olive oil + extra for greasing vegetables and meat
• 0.5 cup sour cream
• 2 tbsp. sour milk or kefir
• 1/4 cup chopped fresh chives
• Juice of half a lemon
• 1 large red onion, sliced ​​into thick rings
• 170 g chopped spinach
• 2-3 tablespoons steak sauce

Preparation:

1. Preheat oven to 200°C (400°F). Prick 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 pieces. In a large bowl, combine the sour cream, buttermilk, chives, and lemon juice, season with salt and pepper. Stir in the potatoes.
2. Meanwhile, preheat the grill to high heat. Brush the steak and onion rings with olive oil and season with salt and pepper. Grill the steak until grill marks appear, about 7 minutes, then turn and cook for another 4-5 minutes for medium-rare.
3. Fry the onion rings until charred, about 2 minutes per side. Transfer the steak and onion rings to a cutting board and let rest for 5 minutes.
4. Coarsely chop the onion rings and combine in a bowl with the spinach, steak sauce, 3 tablespoons of olive oil, and salt and pepper to taste. Slice the steak thinly.
5. Divide the salad among plates, place the meat on top and serve with potatoes.