Back bacon -- what might be called Canadian Bacon -- is pretty lean, hereabouts. The hard part is getting it without the cornmeal. (It's more or less smoked pork loin, the stuff that gets rolled up into pork roasts. If you have a smoker, unrolling a roast or two would work.)

Or just ham; if you've got a source of decent ham this lunch application is more or less what smoked pork generally is for. (Reasonably priced smoked pork shoulder is a lot to wish for.)

[Edited to add -- real pemmican, with buffalo and saskatoon berries, is amazing. Venison or just beef can be excellent but it's got a bad work/mass ratio in terms of results.)