Potatoes With Onions and Mushrooms

50 oz potatoes
7 oz mushrooms
3 onions
1 cup water
½ cup olive oil
1 teaspoon salt
½ teaspoon pepper
Peel potatoes. Cut into rings, potatoes, mushrooms and onions, season and mix well.
Put seasoned potatoes, mushrooms and onions in the glass dish and add 1 cup water.
Reheat the oven and put dish in it on 400 F.
Mix again all potatoes, mushrooms and onions after 15 minutes.
Return dish in oven, for another 15 minutes.
Serve immediately.Source : allrecipes.com