Instructions

1. Wash and rub the potatoes (no need to peel), then put them in a pan of cold water and bring to the boil. Simmer for about 10 minutes until tender, then drain and keep warm.
2. Heat the barbecue or griddle pan.
3. Brush the steak with some oil, season with salt, then cook for a couple minutes each side for medium or longer if you like it well done. Transfer to a plate and rest it (covered).
4. Cut the potatoes in half, brush with a little oil, and cook them until charred marks appear. Slice the courgettes, brush them with some oil and cook until tender.
5. Slice the radish and, in a large serving dish, toss with the watercress.
6. Mix the yoghurt with horseradish and lemon juice. Chop the mint leaves, add to the dressing.
7. Slice the steak about 1cm thick then add it to the salad together with the potatoes and courgette. Season to taste and drizzle with the dressing.
8. Serve lukewarm.