Peel the turnips and cut them in half lengthways. Put the cut ends flat against your chopping board and cut them, lengthways, into 1cm/½ inch thick slices.
Heat the oil in a fairly wide pot over a medium-high flame. When hot, put in the tomatoes. Stir and fry for about 2 minutes. Add the ginger, ground coriander, turmeric and cayenne. Stir and fry for another 2