Preheat the oven to 400 degrees F.
In a medium bowl, mix the flour, baking powder, and salt. Add the margarine and with your hands, mix in to make a fine crumb.
Add just enough water for the dough to come together completely. The dough shouldn't be wet. Set aside.
Heat skillet to medium heat, add olive oil and all the vegetables and lentils. The lentils are optional because sometimes they don't cook all the way and can be a little crunchy. You might want to cook them partially through ahead of time, leave them out, or add 3/4 c of veggie stock and let the vegetables simmer longer. Saute the vegetables for about 5 minutes then add the stock. cook until the vegetables are tender.

Meanwhile, make gravy (or if you have some on hand, warm it up).
Once the vegetables are done, mix them with the gravy. You can use any proportion of gravy to vegetables you want. I had there be a little left over gravy to put on top of the pasties. Set filling aside.
Roll out your pastie dough to be 1/8 of an inch thick. Cut out 6 inch circles.
Add about a half a cup or so filling to the circles, enough so that they'll be full but not overflowing. fold into a semi-circle, and pinch the edges shut (or do some fancy crimping!).
Place on a cookie sheet lined with foil for easy clean up. Bake in the oven for about 15 minutes until the bottoms are golden brown, which will brown much faster than the tops.
Serve topped with gravy if you'd like. They'll keep overnight. To reheat, place in the over at 350F for ten minutes.

Crust:
1 stick margarine (or other substitute) cold and cubed
1 3/4 cup flour
2 1/2 teaspoon baking powder
3/4 teaspoon salt
a few tablespoon water

Filling:
2-3 tablespoon olive oil
2-3 medium potatoes, diced
2 carrots, diced
1 small-medium onion, diced
1/3 cup lentils, optional
1/2 cup strong veggie stock
+ one recipe gravy (or use your own)