jlambe

Create a Poedit project for your theme if you haven't already, and make sure to add __ on the Sources keywords tab and other gettext functions declared in WordPress: _e, ...
Go to Edit->Preferences.
On the Parsers tab, add a new parser with these settings:
Language: Twig
List of extensions: *.twig
Parser command: xgettext --language=Python --add-comments=TRANSLATORS --force-po -o %o %C %K %F
An item in keyword list: -k%k
An item in input files list: %f
Source code charset: --from-code=%c
Save and Update!