Combine all ingredients in a food processor, blend until very smooth. (Or use a stick blender). Use water to adjust consistency as required.

Adjust lemon or lime as required, and add salt to taste (bearing in mind saltiness of the food you are serving it with). Should have a bit of tang if intended to be paired with rich, bold flavoured food like Mexican food.

Keeps for 4 days in an airtight container - and stays green!