Preheat a barbecue grill or char-grill pan over a high heat. Brush both sides of bread and mushrooms with oil. Char-grill bread for 2 minutes each side then char-grill mushrooms for 3 minutes on each side or until tender. Remove.
Meanwhile, bring a medium saucepan of water to the boil. Gently add eggs and stir until water returns to the boil. Cook for 4 ½ minutes for soft-boiled eggs, or until cooked to your liking. Drain and refresh under cold water. Gently crack shells and peel.
Combine avocado, onions and lemon juice. Season. Mix well. Spread labneh over bread. Top with mushrooms. Spoon over avocado.Break eggs in half and arrange on top. Sprinkle with lemon rind and micro-cress. Serve.