Just use mashed potatoes, vegetarian gravy, lots of mixed
veggies. You don't even need the meat in it. if you want to
substitute, you could use the various tofu crumbles, "wheat
meat" crumbles, get some basic boca burgers, cook it up and
smash it into small pieces and put it in there instead. Veggie
sausage would work too, or you could try using cooked lentils
for the meat portion. The beauty of shephards pie is that its
really simple, and there's no real wrong way to do it. "
