Valéria's Cuisine - Fried Mushroom Pie

Ingredients

• Dough: 200 g (7 oz) wheat flour
• 100 g (3.5 oz) margarine
• 1 teaspoon baking powder
• 1 egg
• 1/2 teaspoon salt
• Filling: 500 g (1 lb) fresh mushrooms
• 3 onions
• 1/2 cup milk
• 1 tablespoon wheat flour
• salt, pepper and oregano
• 100 g (3.5 oz) grated or sliced cheese
• 1 big tomato