Over medium heat, sweat onions, celery, peppers, and chillies for about 10 minutes.
Stir in the vegan mince and cook for about 5 minutes to absorb all the flavours.
Stir in chili powder and all the remaining ingredients, cover, and simmer over low heat for at least half an hour.
Turn off heat and let stand overnight. Reheat and serve the following day in a bowl with fresh spring onions, fresh coriander and vegan yogurt on top. If you're English, you'll feel compelled to serve this over rice, but it is completely unnecessary.
Like all tomato based sauces, this recipe only improves with age. I like it best after about five days, but it's always gone before then.