In a jar or smaller bowl, use an immersion blender or whisk to blend the egg yolks and apple cider vinegar until frothy.
Start out very slow and add a little bit of your bacon grease. Blend well.
Continue to add your bacon grease a small amount at a time, blending fully after each time.
You will start to get a thick and creamy sauce.
Once all the grease is blended, add the salt, pepper, and dijon mustard.
Mix well and enjoy!
See notes for tips on your emulsion and troubleshooting.