Toss all of the ingredients together right in your serving dish, then season to taste with salt. Chill until you're ready to serve.
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Notes
The pico's flavor will get better over time. You can serve it immediately, but if you can wait 15-20 minutes, the flavors will meld a bit, making it even more delicious.It will keep for about 3 days in the refrigerator, so you can also make it in advance!