Garlic Sumac Prawns with Lemon Rice

4 tbsp olive oil
1 onion, halved and finely sliced
300g long-grain rice
550ml water or stock
1 tsp salt
1 tsp turmeric
2 tbsp lemon juice and 1 tbsp lemon zest; or
1 wedge of preserved lemon rind, diced
3 garlic cloves, finely sliced
12 medium prawns, peeled, deveined with tails left
1/2 tsp cayenne pepper
1 tsp ground coriander
1 tsp sumac and extra for serving
2 tbsp chopped parsley
2 tbsp chopped mint
1 lemon, cut into wedges

Heat two tablespoons of oil in a frypan and cook onion gently for five minutes. Rinse the rice under cold running water, shake dry and add to the onions, tossing well. Add water, salt, turmeric, lemon juice and zest ( or preserved lemon) and bring to the boil. Cover tightly, reduce the heat to very low and simmer for 15 minutes. Remove from heat and leave to rest, covered, while cooking the prawns. Heat remaining oil in frypan and cook garlic over medium heat. Add prawns, cayenne, coriander and sumac, tossing well until the prawns are cooked and the garlic is golden and nutty. Toss parsley and mint through rice, top with prawns, garlic, a final dusting of sumac and lemon wedges for squeezing.