Method
Preheat your grill, or prepare your barbecue so that it’s ready for cooking (see our handy guide, Getting the Most from a Charcoal Barbecue for some useful tips). Put the potatoes into a pan and fill with enough cold water to cover. On the hob, bring them to the boil then cook for about 10 minutes – the potatoes should be tender but not too soft. Drain then set aside, covering the potatoes to keep them warm.

Season both sides of the steak with salt and pepper, then place them under the grill or on the barbecue for about 6-8 minutes per side (or less or more, to your taste). While the steaks are cooking, make the dressing by whisking together the oil, vinegar, mustard and tarragon, and season to taste with salt and pepper. Divide the salad leaves, tomatoes and red onion between four plates, then slice the warm potatoes into halves and share between the plates. Carve the cooked steaks into thick strips and lay them across the top of each plate of salad, then drizzle generously with the dressing and serve.