Put the potatoes on double tin foil and sprinkle with 2 spoons olive oil, rosemary and pepper and salt. Fold in and put in 180°C (356°F) Kamado BBQ on the sides for 20 minutes while turning a few times.
Mix the crème fraîche with the lemon juice, chives and season with pepper and salt. Grill the steaks for 4-5 minutes a side.
Cut the potato crosswise, fill with a big spoon of crème fraîche and serve with the steak.