Peel and finely chop the garlic and set aside. Place a large frying pan over a medium-to-high heat and, when hot, add the olive oil. Carefully separate the oyster mushrooms and place them, gill-side down, in the pan so they all fit in one layer. Fry for 45-60 seconds until golden on one side, salt lightly, then turn and cook for 30 seconds more.
 

Add the garlic in between the mushrooms (there should be a little more space now they are cooked) and fry for another 30 seconds. Pour in the sherry, bubble for a minute or two, then add the prawns. Stir until the prawns are warmed through, finely chop the parsley then sprinkle over the prawns and check for seasoning. Serve on toasted rustic bread.