Make the batter: sift the flour into a bowl and beat in the egg and milk and water until smooth. Heat a knob of lard in a small frying pan tilting the pan so that the melted lard coats the base. Pour in enough batter to cover the base of the pan and cook for about 3 minutes until golden underneath. Turn and cook the other side. Repeat with remaining batter to make eight pancakes.

Add the bacon to the pan and fry in its own fat for a few minutes.

Add the mushrooms and onions to the pan. Cook gently, stirring until the vegetables are soft and there is no free liquid. Season well.

Fill the pancakes with the bacon mixture and roll up like a parcel with the ends tucked in to enclose the filling. Secure with cocktail sticks.

Heat the oil and deep-fry the pancakes quickly for about 2 minutes, or until crisp. Drain and serve the blintzes at once.