Very deliberately peel the oranges; next slice into rings cutting away all the pith, or the albedo, if you wanted to get technical. Then dice the segments into small chunks discarding all of the white central column. Ideally, you want only the inner juicy vesicles. It does take care, but is worth it. You can use most of the other parts in other recipes, so reserve what you can.
Mince the red onion into a small uniform cut. Cut the jalapeño pepper in half and remove the seeds. Continue to dice the pepper into small squares (@1/4 inch). Gently toss the oranges, onions and peppers together in a small bowl. Roll the mint leaves up and snip into a chiffonade and/or chop the cilantro. You can Add these to the bowl.
Juice half a lime into the bowl. Stir everything together. Drizzle a bit of very fine EVOO. Add a pinch of the Maldon salt flakes to finish. Refrigerate for 30 minutes and serve. This works nicely as a refreshing condiment with beef, chicken or duck, or as a side salad.