Take two large red onions and slice finely.
Place the onion in a bowl and cover with boiling water.
Allow to steep for one minute and then drain.
Add the juice of five limes (one cup of lime juice), the juice of two oranges and 1 tsp Maldon salt. At this point you could add a very finely chopped fresh red chilli.
Mix thoroughly and place in a lidded container in the fridge overnight.
The juice will turn pink and the onion will be slightly pickled but still crunchy.
Serve with any smoked meat or burger. It goes especially well with pulled pork.