What you need:

Red onions, boiling water, salt, and lime juice.

1. Slice

Slice the onions thinly and put them in a heat-safe bowl.

2. Blanch

Pour boiling water over and let stand for 30 seconds. Drain.

3. Salt

Add the salt and toss to distribute throughout.

4. Lime Juice

Squeeze the limes over the onions, enough to cover. Stir.

5. Let Stand

Let the onions marinate in the lime juice and salt for 30 minutes.

Serve on everything!