1. Place the yogurt, stock, ginger, cumin and chilli powder in a food processor and blend until smooth.
2. Transfer to a mixing bowl.
3. Finely dice the cucumber, deseed and finely dice the tomatoes and add to the yogurt mixture with the copped mint.
4. Season well and stir to combine evenly.
5. Cover and chill in the refrigerator for 30 minutes before serving.
6. Drizzle over a little yogurt and sprinkle over some roasted cumin seeds before serving.