1. To prepare the pesto, blend walnuts, jalapeno pepper, cilantro, vinegar, salt and 2 to 3 tblsp water to a fine paste, using a food processor.
2. Remove the paste in a bowl adjust consistency using water and season it, if required. Refirgerate till further use.
3. Use as a spread, dip, or for garnishing soups or refrigerate in an airtight container.