Heat water in a pot or kettle until boiling.

Wash the bell peppers.

Remove the seeds from the bell peppers and slice them into very thin strips.

Blanch the pepper strips in the boiling water for about 10 minutes.

Peel and finely chop the onion.

Heat a pot over medium heat without adding oil. Once the pot is hot, add olive oil, wait a few moments, then sauté the chopped onion.

Drain the bell peppers and add them to the pot.

Cover and cook over low heat for about 20 minutes, stirring occasionally.