Soak the barley in boiling water while you prepare your veggies. Preheat the oven to 180C
Heat olive oil in an oven proof pan with a lid and add the leeks and garlic. Saute for a few minutes until the leek is soft and slightly golden on the edges. Add the mushrooms and sauce for a further 3 to 4 minutes until soft.
Drain the barley thoroughly then add it to the pan with the stock, lemon juice and water. Season with pepper and bring to the boil.
Remove from the heat, cover and place in the oven to cook for 40 minutes.
Serve with shaved parmesan and steamed spinach or green salad.