Rather than punish we interrupt undesirable behaviors with a simple noise, like kissing or clicking. You are going to reward the dog's coming to you with the biggest best reward you have available. Begin using the interrupter when you dog isn't doing anything wrong, just give them every opportunity to get rewarded for coming right to you every time you make that noise. Don't just put down the bowl of food, measure out the regular amount for the meal and grab a handful of kibble and begin training. Stand near your dog and make the noise, did he look at you? Say "Yes" and toss the dog a piece of kibble. Walk away. Does the dog follow? No, then take two or three steps and make the noise. Say "yes" for either a look or a step toward you, and kneel down and offer another piece of kibble. Don't lean over the dog, most are made uncomfortable with a large body looming over them. Have the dog come right to you to get the reward and before you give the treat gently put one finger on the collar. This is to interrupt some behavior so you might want to have actual physical control over your dog and being able to touch and grab the collar will give you that control. You might have interrupted your dog's investigating a snake in the grass, I would bet that you wouldn't want your dog to go back to investigate some more.