Sift the flour into a bowl, crack the egg in the centre and add salt and pepper to taste. Gradually whisk in the milk until smooth. It can stand a while.
Coat the sliced onion in oil and sugar and spread over a baking tray. Put the sausages in a Pyrex glass bowl or a heavy bottomed roasting pan and put both in the oven.
When the sausages are cooked (10-15 minutes) add a spoon of oil then pour in the batter. Return to the oven and bake 30 minutes.
Heat the stock in a small saucepan. Add the Worchestershire sauce and mustard powder. When the onions are blackening, sprinkle them with the flour and add them to the stock, stirring with a fork until smooth.
Serve the sausages and batter with the onion gravy poured on top.
Recipe courtesy of allrecipes.co.nz
Serving size 4