Recipe Fridays: Shepard's Pie three ways

I know it sounds a little dated, but I've just realized Shepard's Pie is an incredibly easy, filling, and impressive-looking main course that can be made vegetarian--the perfect winter meal in my house.

Shepard's pie (serves 4)
6 potatoes
2 cups either cooked lentils, ground beef, or ground beef-style soy
1 large carrot
1 large green pepper
1 onion
2 tomatoes
spices: salt, pepper, thyme, paprika, cinnamon, and nutmeg are good (as in all of them, or a meat seasoning mix)
Garlic, butter, and cheese (if desired) for mashed potatoes

Peel the potatoes and cut into pieces.  Boil until tender.  Meanwhile, chop all vegetables.  Saute onion in large skillet with olive oil until translucent.   If using ground beef, add at this point, and cook for 5 minutes, then add carrot and tomatoes.  If using soy or lentils, first add carrots and tomatoes.  Saute until carrots begin to tenderize.  Then add soy or lentils, and cook until heated through and carrots are tender.  Last, stir in spices and green peppers and remove from heat.

Mash potatoes with garlic, butter, and cheese to taste (also salt, of course).  Scrape meat/soy/lentil mixture into round casserole dish.  Spoon potatoes on top in pretty pattern, and then "rough up" top with a fork to encourage crisping.  Place in either a 400 degree oven for 30 minutes, or, if you're hungry, under the broiler for 10 (monitoring and turning as needed).  Remove when potatoes are browned in places.

Serve with a green salad with quick pickled onions: Heat 1/2 cup vinegar, 1 tsp salt, and 1 Tb sugar until boiling.  Add thinly sliced red onion (rounds) and return to boil.  Remove from heat and let sit for 30 minutes, until onions are soft and bright pink.