Rinse rice with cold water. Place in a saucepan and pour in the 600ml water. Bring to the boil, turn down the heat and simmer covered for 50 minutes (or according to packet instructions), until soft and fluffy. Remove from the heat and allow to cool.
Peel cucumbers (if you have organic cucumbers, you can leave the peel on), cut in half lengthways and scrape out the seeds with a teaspoon. Dice the cucumbers and place into a salad bowl. Mix with cooled rice.
In a small bowl whisk together yoghurt, oil, lemon juice and vinegar. Season with salt and pepper to taste and pour over rice. Add coriander and spring onions and toss. Place in the fridge for at least 30 minutes or until it is time to serve, also allowing for the flavours to develop.