Using a spoon, scoop the flesh of the avocados into a food processor or blender. Add the cilantro, lime juice, jalapeño, water, and salt.
Process, stopping to scrape down the sides as necessary, until the sauce is smooth and creamy. If the mixture refuses to blend, add additional water in 1-tablespoon increments as necessary.
If you would like a thinner, more drizzly sauce, add water in 1-tablespoon increments until it reaches your desired consistency. Taste, and add more salt if needed.
Transfer to a small serving bowl. Keeps well in the refrigerator, covered, for about 4 days.