Stir water, lentils and salt in small saucepan. Cover and bring to a boil. Remove lid, dropheat to simmer and cook for 35-40 minutes, until water is absorbed and lentils are al dente. Remove from heat.
Heat oven to 400°F. Crumble mushrooms into large roasting tray.
Roughly chop parsley, garlic and walnuts. Scatter over mushrooms.
Pour oil over vegetables add salt and pepper, stir to combine.
Roast vegetables for 15 minutes, until mushrooms are withered and walnuts are toasted.
Remove vegetables from oven, stir into finished lentils. Add balsamic vinegar and flaxseed.