Put the sliced onion in a small bowl, add a tablespoon of lime juice and a quarter-teaspoon of salt, then scrunch with your hands a few times and put to one side.
Wash the rice in a sieve under cold running water until it runs clear, then put it in a large pot and add plenty of just-boiled water.
Bring back to a boil, cook for 10 minutes, then add the green beans and cook for a further eight minutes, or until both the rice and beans are tender.
While the rice and beans are cooking, make the dressing.
In an empty jam jar, combine the olive oil, pomegranate molasses, honey, sumac, the remaining lime juice and three-quarters of a teaspoon of salt, seal and give it all a good shake until emulsified.
Put the drained cannellini beans, cooked green beans, cooked rice and chopped herbs in a large bowl, drizzle over the dressing and give the mix a good toss until well coated.
Break the feta into chunks with your hands, scatter over the rice and lightly toss again.
Tip out on to a platter, finish with the quick pickled onions and a sprinkle of sumac, and serve at room temperature.
