Brian,
Type "pesto" in the search box. Then limit by recipe type, then dish type, then "dips, spreads, and salsas". Another method is to limit by recipe type, then side dishes, then "sauces, general". A pesto recipe may be indexed as either recipe type, or both types.
If you get too many pesto recipes from these options, try: 1) adding additional ingredients in the search box; or 2) limit by ingredient / herbs and spices; or 3) limit by ethnicity (either Italian or French for traditional pesto).
Good luck!