1 Scrub the potatoes thoroughly and cook in boiling water for 15 to 20 minutes. Peel and finely chop the shallot. Peel the carrots. Wash and trim the courgettes. Cut the vegetables into thin strips. Wash, dry and chop the herbs.
2 Mix the quark with the milk and herbs. Season with salt and pepper. Heat the oil and sweat the shallot, carrots and courgettes over a medium heat for about 3 minutes. Season with lime juice, salt, pepper and nutmeg.
3 Cook the steaks in a grill pan or on the barbecue for about 3 - 5 minutes each side, according to thickness and preference. Season with salt and pepper. Drain the potatoes, leave to dry and make a lengthwise cut in each potato. Top with quark and serve on plates with the steaks, the vegetables and sorrel, cut into thin strips or chopped.