Place the mushrooms in a small heatproof bowl and cover with boiling water. Stand for 10–15 minutes or until tender (see note). Drain and roughly chop.
Meanwhile, heat 1 tablespoon oil in a frying pan over medium high heat. Add the onion and garlic. Cook, stirring, for 3–4 minutes or until onion is soft. Remove to a bowl. Add the mushrooms, goat’s cheese and parsley. Season with salt and pepper.
Cut a pocket through the centre of each lamb cutlet. Fill with mushroom mixture. Secure with a toothpick.
Preheat a barbecue plate on medium heat. Brush both sides of the lamb with remaining oil and season with salt and pepper. Barbecue lamb for 3–4 minutes on each side for medium or until cooked to your liking. Remove to a tray. Cover and stand for 5 minutes to rest. Remove the toothpicks.
Serve with barbecued flat bread, rocket and lemon wedges.