Place the minced lamb, red onion, garlic, rosemary and mint into a bowl and mix well.
Divide the mince mixture into six equal portions and mould into patties.
Heat a griddle pan until smoking. Rub the patties with oil and griddle for 5-6 minutes on each side, or until completely cooked through.
For the salad, heat one tablespoon of the olive oil in a pan and fry the onion for 5-6 minutes, until softened. Transfer to a clean bowl.
Add the harissa paste, chickpeas, natural yoghurt, the remaining olive oil, lime juice and mint to the bowl of fried onions and mix together well.
To serve, place a piece of grilled focaccia onto each of six plates. Top each piece with a small handful of watercress.
Place a lamb burger on top of each pile of watercress, then top with a spoonful of the spicy chickpea salad.
