Hot Mushroom Dip

1 pound of mushrooms sliced
1 onion chopped fine
1 cup sour cream
1/3 cup fresh shredded parmesan cheese
3 tablespoons butter
2 teaspoons flour 
1/2 teaspoon lemon juice
1/2 teaspoon salt
1/4 teaspoon pepper

Suate onions in butter about 5 minutes. Sprinkle with flour and cook another 5 minutes. Add sour cream, lemon juice salt and pepper. Pour into a shallow casserole dish and top with the parmesan cheese. Bake at 375° for 20 minutes. Serve warm with crackers or tortilla chips.