Sour Mashed Sweet Potato

Peel and roast the sweet potato or other vegetables. Ideally, this would be an extra piece of sweet potato, pumpkin, taro etc. tossed into the oven with other food being roasted for a main meal. A 500g piece of sweet potato will roast nicely in 1½ hours at 150°C (300°F), or less at a higher temperature.

Allow the vegetables to cool to about room temperature.

Mash the vegetables in a bowl. Try to break up all large pieces, but don't be too fussy – a few little lumps won't bother anyone!

Peel the ginger, and mash it in a mortar and pestle or mince it in a food processor. Add it to the bowl and mix well.

Add the salt and kefir or yoghurt, and mix in well. Try to get a smooth consistency, but don't be too concerned about the odd lump.

Pack the mash into a crock or jar, where it can ferment. Pick a nice looking one that you can serve it from later also. Smooth the top of the mash with a spatula.

Fill a strong plastic bag with water, seal (knot or zip-lock) and place on top of the mash. Because the plastic bag is flexible, it will fit to the surface of the mash and exclude air, which prevents mould.

Set aside in a warm place (not hot!) for 48 hours to ferment.

After fermenting, remove the plastic bag and close the crock or jar with a lid, then place in a refrigerator to keep fresh.