I've just checked with the crtl+H Find/Replace dialog, and (even!) discovered that this is lurking under Replace in the Editing tools on the ribbon …

1. open the Replace dialog
2. click the [More] button
3. select Font from the Format pulldown
4. select (check) Strikethrough from the Find Font dialog
5. close the Find Font dialog
6. click [Find next] in the Find and Replace dialog

Takes less time to do than it does to describe …