On-leash, no distractions
For this lesson, you will need to have your dog on-leash. Take them outside on a walk. Let them saturate in the smells and sounds so they are less distracted. Cue your recall, happy talking if necessary, and feed your dog close to your leg. Do this just one time per walk (to keep it novel) and when your dog least expects it. Avoid practicing in the exact same location each time!
Practise daily over the course of a few days before moving on.