Cook the rice in the water with the stock cube until the rice is done - about 40 minutes. Drain then let it cool a little.
While the rice is cooking prepare the dressing by putting all the ingredients in a jar with a lid and giving it a good shake. Also chop the tomatoes, spring onions and parsley. Drain the lentils.
When the rice has cooled a little but is still warm mix all the ingredients in. Add the dressing and mix through. Let it chill for an hour or so if possible BUT I prefer to eat it at room temperature.