Heat oven to 220C/200C fan/gas 7 and lightly oil a baking tray. Mix the vinegar with the almond milk and set aside. Bring a saucepan of water to the boil, add the cauliflower stalk and cook for 5 mins until almost tender. Drain well, leave to cool, then finely chop.
Mix the flour, baking powder, nutritional yeast, spices, thyme leaves and 1 tsp salt in a large bowl. Add the cauliflower, then add the oil and pour in 230ml of the soured almond milk. Working quickly, bring the mixture together with a wooden spoon; if there is any dry mixture in the bowl, add more almond milk to make a soft but not sticky dough. Tip the dough onto a floured work surface and pat to a thickness of about 2.5cm. Cut out rounds with a 6cm fluted cutter and transfer to the baking tray. Gather together any offcuts and cut out more rounds.
Bake on the top shelf of the oven for 10-12 mins until golden. Serve warm with onion chutney.