Mix together and serve immediately or cover and refrigerate until ready to serve.
Notes
Let it sit. If you have time, I recommend letting the salsa sit in the fridge for at least 30 minutes to 1 hour to help the flavors and juices really meld together and soak into the corn and beans.
Use fresh if available. If it's summertime and you want to take advantage of using fresh corn, do it! You'll need about 1 ½ cups of freshly cooked corn, which is about 3-4 ears of fresh corn. You can boil the ears of corn, saute it in some butter, or grill it for a smoky charred flavor.