Preheat the oven to 200C/Gas Mark 6. Tip the flour into a bowl, make a well in the centre, crack in the eggs and whisk. Add the salt and then whisk in the milk until you have a smooth, runny batter. Set aside for 15 minutes, while you cook the sausages.
Add the fats to a pan, heat until bubbling and fry the sausages over a medium heat until they are cooked. Allow them to blacken and blister in places.
Scatter the herbs over the sausages, stalks and all. Pour the batter into the smoking hot pan, around the cooked sausages. It may spit a bit, so protect your arms with a tea towel. Put the tin straight into the hot oven. Bake for 25–30 minutes, pulling it out when the batter is risen, crisp and browned in patches.
While the toad-in-the-hole is in the oven, make the gravy. Melt the butter in the saucepan and, once it is bubbling, add the onions. Cook for 10 minutes over a medium heat until softened.
Add the sugar, stirring until it has dissolved into the butter. Pour in the Worcestershire sauce, and stir through. Sprinkle in the flour and stir to coat the onion. Pour in about 100ml of the stock and whisk until the sauce surrounding the onions is smooth. Add the rest of the liquid and bring to the boil, stirring with the wooden spoon until thick. Remove from the heat and warm again when you’re ready to serve. Season to taste.
Remove the toad-in-the-hole from the oven and serve immediately. Make sure that everyone has plenty of crispy bits from the sides of the dish and a generous slug of the gravy.