While we were staying with our friends in the South I noticed a jar on the windowsill. It contained a yellowish liquid and had things floating in it. I didn't like to ask what it was.

However, the next day N asked me if I'd like to taste her homemade 'lemonade' and after I'd drunk it she told me it was water kefir and pointed to the ominous looking jar.

Apparently there are two types of kefir crystals; one for fermenting milk and the other for use in water based drinks. The water variety are opaque white blobs. You keep them in sugar solution in the fridge for up to a fortnight when they are not in use but if you want to store them longer you have to dry them out. In their dehydrated state they ressemble brown sugar. 

She had dried some for me to bring home and after carefully reconstituting them over four days I went into production and soon had my own jars of bubbling liquids on the go.

No-one else in the family is prepared to taste the results despite the promised health benefits. It is said to be good for the digestion and stress, among other things. I have to admit it smells pretty strange but, honestly, it doesn't taste that bad, even if I have to admit I do need to refine my recipe.

The basic idea is to put the crystals in sugared water together with some dried fruit - preferably a fig - and a quarter of an organic (untreated) lemon. You give it a good stir every day and once the fruit has all risen to the surface it is ready to strain and drink.

I found a recipe for 'healthy champagne' made with freshly squeezed grape juice and water kefir, which promises a sparkling 'wine'. At the moment it looks cloudy and rather unappetising despite the lively fermentation.

Who knows how it might be transformed in the next 48 hours. One can but hope.