What is the mother in cider vinegar?
A natural culture of bacteria and yeast that forms during fermentation. It makes raw, unfiltered vinegar look cloudy or stringy. It is entirely normal and a sign it has not been filtered or pasteurised.
Can I cook with extra virgin olive oil?
Yes, for everyday cooking and moderate heat. For high-temperature frying, coconut or rapeseed are better suited - and it is a waste of a good peppery olive oil either way.
How should I store oil?
Cool, dark and away from the hob. Warmth and daylight age an oil faster than anything else, and next to the cooker is the worst place in the kitchen for it.
Why is one balsamic five times the price of another?
Ageing, and what is in it. A long-aged balsamic is thick, sweet and made from grape must alone; a cheap one is wine vinegar with colouring and sweetener. The ingredient list gives it away.