Advanced search allows users to apply specific filters (i.e. course, include ingredients, excplude ingredients, dietary restrictions) to recipe searches. To perform an advanced search, from the home screen (also known as Get Ideas), select the search icon located on the upper right, and perform a general search. On the results screen, select the advanced search icon located on the lower right, adjust the desired fields, and hit the regular search icon -- the results will be updated to reflect the new filters.
Please note that advanced search filters like dietary restrictions and the ability to exclude certain ingredients are only available with a Pro subscription.