Preparation 1. Season portobellos with salt, pepper and thyme. Grill over medium heat. Turn portobellos over to be used as bases and set aside. 2. Saute all other mushroos with onions and chives. 3. Remove from heat. Mix cooked mushrooms with cheese and mayonnaise. 4. Spoon mushroom mixture on portobellos and bake at 180°C for 10 minutes. 5. Sprinkle more chives before serving with rocket salad on side.