Chop the scallops into small pieces - around 8 pieces per large scallop, 4 for small ones. Put in a bowl with the lemon and lime juices and diced chili, mix and then place in the fridge. Leave for a good 2 hours or more until the scallops go opaque.
Once ready, add the chopped onion and cilantro, mix and serve. Suggest serving with plantain chips/tostones (or as I had, fried plantain slices - around ½ plantain) or a simple salad.