Prepare the ingredients. Use high-quality extra virgin olive oil for the best flavor. For the cilantro, use only the leaves, not the stems, as stems can make the marinade bitter. Place all the ingredients in a blender or food processor.

Blend or process until everything is well combined. The marinade is ready to use. Pour it into a jar or bowl. If you don't use it all, you can freeze the leftovers for future use.

I used this marinade to prepare tilapia fillets, and they turned out great.