Goal: Horse leaves a pile of freshly-picked grass on a raised surface with no cue for two minutes. (This is also a default food zen in your presence like the treat pouch is.)
If your horse does not know how to eat off a raised surface, start with food in your hand and c/t for him to eat it and gradually lower it until your hand is lying flat on the top of a upturned bucket or other raised surface.
Next, place the lowest level food on an inverted bucket and start training from step 1 above. Do not cue the behavior. At first, be prepared to cover the food with your hand so he can’t get it. Remove your hand when you c/t and aloow him to eat.
Try to avoid allowing him get the food when he has not yet been c/t since you want him to learn that holding himself back is what earns him the reward, not grabbing for it. All it takes is a few successful grabs to learn that if he tries once in a while, he just might be successful. This can take a long time to retrain so best to be overly careful preventing that behavior from developing the first time.
Increase the value of the food as he is successful as in step 1 to 5. Do not add a cue. This is how it becomes a default behavior, with the presence of the food on the bucket or surface as being the cue. If you would prefer him leaving the food alone to be a cued behavior, simply add the release cue just before the click. Then drop the click and just use the release cue. (some people use a dropped lead rope as a cue that it is okay for your horse to eat while resting on a trail ride, for example.)
Increase the time that he must leave the food as before to one minute or more.