1. Preheat the oven to 175°C (350°F). Slice the roast beef into thin strips and season with salt and pepper. Place the strips on a baking sheet and roast for 20 minutes, or until cooked to your desired level of doneness.

2. Boil the potatoes until tender, then dice and set aside. Whisk together 120ml (1/2 cup) of crème fraîche and 1 tablespoon of Dijon mustard. Add the diced potatoes, 30g (1/4 cup) of chopped parsley, and a pinch of salt and pepper. Mix well to combine.

3. Combine 120ml (1/2 cup) of crème fraîche and 30g (1/4 cup) of crumbled feta cheese. Mix until smooth and creamy.

4. Slice the roasted beef into thin strips and place on a platter or individual plates. Spoon the potato salad alongside the beef, and top with a dollop of feta cream. Serve immediately.