Preheat oven to Gas 7/425f/220c.

1 You'll need a solid flameproof roasting tin with a base of 9 x 6"/23 x 15cm, 2"/5cm deep, and a baking tray 14 x 10"/35 x 25.5cm.

2 For the Batter: Sieve the flour into a large bowl, holding the sieve up high to air the flour. With the back of a spoon, make a well in the centre, break in the egg and add salt and pepper.

3 Measure the milk and water in a measuring jug, and with an electric hand whisk on a slow speed, begin to whisk the egg into the flour. As you whisk, the flour around the edges will slowly be incorporated.

4 Add the liquid gradually, stopping to scrape the flour into the mixture and whisk until the batter is smooth. Now it's ready to use, though it's rumoured that batter left to stand is better.

5 Put the sliced onions in a bowl, add 1 tsp oil and the sugar, and toss the onions around to get the lightest coating. Then spread on a baking tray.

6 Put the sausages in the roasting tin, place the onions on a high shelf in the oven and the sausages on a lower shelf and set a timer for 10 minutes. When the timer goes off, remove the sausages but cook the onions for 4-5 minutes more until blackened around the edges.

7 When the onions are ready, remove and leave to one side. Put the roasting tin containing the sausages on a direct heat turned to medium and, if the sausages haven't released much fat, add 1 tbsp oil.

8 When the tin is really hot and the oil starting to simmer - it must be searing hot - quickly pour the batter in around the sausages.

9 Immediately put the roasting tin back into the oven on the highest shelf and cook the whole thing for 30 minutes.

10 For the Gravy: Add the mustard powder and Worcestershire sauce to the stock, and add the onions from the baking tray to a medium-sized pan. Add a teaspoon of oil and, using a wooden spoon, stir in the plain flour.

11 Stir together on a medium heat and whisk, gradually adding the stock to the pan, and whisking all the time until it's all in.

12 Gently simmer for five minutes. Check the seasoning and pour into a warmed serving jug. The toad should be puffed brown and crisp when ready, with the centre cooked and not too squidgy. Serve immediately with the gravy and mashed potato if desired.

Per serving: 75 Calories (kcal); 3g Total Fat; (30% calories from fat); 4g Protein; 9g Carbohydrate; 94mg Cholesterol; 32mg Sodium Food Exchanges: 0 Grain(Starch); 1/2 Lean Meat; 1 1/2 Vegetable; 0 Fruit; 0 Fat; 0 Other Carbohydrates