This can be done on any of the tabs on the Review Actions screen. But a seperate tab means you do not have to tweak the settings of other tabs.
To quickly search all the items, I created a new tab in the Review Actions Screen. This new tab called "All" helps me to search quickly through out the database. This is how I have done it:
1. Tools -> Options
2. Click on the "Action Screens" icon
3. Click on the + icon in the bottom screen
4. Replace the ... text in the new row with whatever name for the tab. I named mine as "All"
5. Relaunch the TR
6. Go to Review Actions Screen. The new tab will appear
7. Click on the Edit Columns icon and select all the columns you want to see. (I have project/thoughts description, Description, Delegated to, Action date, context, Priority, Topic). Click OK
8. Click on Select Filters Screen and select all the filters you would want to filter on. Remeber to tick both "Use" and "Show" for Search. (I have the following settings: Done, Status, Priority, Topic, Action Date >, Action Date < and Search. Both Use and Show are ticked for all these fields).
9. Click on "Show/Hide Filters" icon to show the filters.
Now you have a separate review action tab for the Search Function. Type in the keyword you remember (descritpion or delegated to). Only the actions which have this keyword will appear. You can use filters to further narrow down.
The only problem is currently "Search" searches in the fields of notes, description or delegated to. It does not search in projects/thoughts desc and topic). So, if your keyword is contained in the project description or in topic and the action description does not contain this keyword, then this action will not appear in the search.