Method

• 1.
  Heat 2 tablespoons oil in a deep frypan, add mushrooms and toss for 3 minutes over medium-high heat. Add garlic and cook for 1 minute, then add vinegar and 2 tablespoons water and toss for a further 2 minutes. Remove from the heat and stir in capsicum. Season, then set aside.
• 2.
  Heat a chargrill pan or large non-stick frypan over medium-high heat. Season lamb and drizzle with remaining olive oil. In batches if necessary, cook steaks for 3 minutes, turning once, for medium-rare, or until cooked to your liking.
• 3.
  Add watercress to mushrooms and toss to combine. Divide lamb and mushrooms among 4 serving plates, then serve immediately.