Heat the oil in a saucepan.
Add the onions and garlic and saute on a low heat until the onions turn translucent.
Season with salt and pepper.
Add the dried basil.
Add the mushrooms and saute for a minute.
Now add the barley and stir for a minute until all the grains are coated with oil.
Add the wine and simmer on a low heat, stirring, until the wine has almost evaporated.
Add the water or stock, 1/2 cup at a time, to the risotto, stirring after each addition. Wait until most of the stock has been absorbed before you add the next 1/2 cup. Do this until the barley is quite tender but has a slight bite to it. This should take about an hour.
Taste and add more salt and pepper if needed.
Add the sour cream and stir around to spread evenly through the risotto.
Turn off heat and mix in the parsley.