Heat the oven to 220C/200C fan/gas 7. Mix the self-raising flour, chickpea flour and baking powder together in a bowl. Add the mustard, soya milk, turmeric and 1 tsp fine salt, then whisk to combine. Lightly whisk the aquafaba in a jug until fluffy, then gently stir into the batter. Leave to rest for 10 mins.

Pour the oil into a large roasting tin and put in the oven to heat up. Tip the sausages into the hot oil and bake for 10-12 mins, shuffling regularly. Add the batter (it should sizzle when it hits the tin) and return to the oven for 25-30 mins, until puffed slightly and golden.

To make the gravy, melt the vegan butter block in a pan and add the red onions and garlic with a large pinch of salt. Cook over a medium heat for 10-12 mins, until soft and lightly caramelised. Add the balsamic vinegar and reduce until it has evaporated. Add the vegetable stock and bring to a simmer. Allow to simmer for 8-10 mins until thickened. Season with salt and pepper.

Cut the toad-in-the-hole into four portions and serve with the gravy on the side.