Slice your onions thinly, following the grain
Put the onions in a strainer and wash them in running water for about 3 min. Taste them; if they are still bitter, repeat the process.
Once the onions are sliced and washed, you can add them to a bowl full of water and ice, and let it rest for 10 min. That will give it an extra crunch.
Remove the onions from the ice bowl and add them to a clean bowl
In the same bowl, add your chilies and cilantro, and mix them
Then add salt, pepper, and lime juice, give it a try, adjust seasoning if needed. it should be acid and salty and at the same time.
Serve with your favorite dish