We started out in the biggest fenced area we could find--in our case it was a grade school baseball park that was almost totally fenced (just open at the gates). We used a 30-ft drag line in case the dog tried to make a break for it. And then we just walked across the field with the dog quartering in front of us.
We train with a whistle recall for field work. Again, the training is in a fenced area.
For out in the field, we attach cow bells to the collars so we can monitor progress through the woods or field. We used to just
use cow bells, but one of our dogs had a grand mal seizure in the woods one day and we realized you can't track them by the bell if they're down and the bell isn't ringing. So we now also add a beeper collar that is set to pointer mode--i.e., it only goes off when the dog is not moving. Before doing any field work, though, we make sure that whistle recall in a safe (fenced) area is as close to 100% as we can get it.
Not sure what kind of terrain or landscape you hope to run your lurcher in...but hope some of that might help