Half-runners need strings removed. To do this effectively, follow the natural curvature of the bean. Cut into the bean on the inside curve at the top or stem end without cutting all the way through and pull the string down the outside edge without pulling it off.
Cut again on the bottom so you can pull the string around the corner and up the inside back to the top.
Done correctly, you should have a one-piece string connected from both sides. Discard the strings.
Cook beans:
Saute the onions in the bacon grease on the saute setting of the instant pot until softened then shut off.
Add the remaining ingredients and the lid, setting it locked and sealed.
Cook at pressure, on high, manual setting for 10 minutes.
Use the quick release, opening when all the steam has dissipated.