Pierogies!

Pastry:
1 1/2 c unbleached allpurpose flour
1/4 t salt
1/4 pound cold unsalted butter, cut in pieces
5 T ice water

Filling:
2 sliced potatoes (boil and mash them) or about 2 c leftover mashed potatoes
3T butter
2 c finely shredded/chopped cabbage
1/4 c onion, finely chopped
1 c cottage cheese
1 1/2 c grated cheese, like sharp cheddar or a nice mix
1 egg
1/2 t salt
2 t dried parsley
1/4 t fresh ground black pepper
Or use nice seasoning blend. The flavors aren't too strong here.
You can also totally add a nice chopped kielbasa to this-it would be great. Or try different meats. But my goal was that of the veg/seafood dish, so I left meat out.

Wash: (OPTIONAL)
1 egg, with 1 T water
poppy or sesame seeds

Dippin' sauce-sour cream, ranch dip, sweet chili dressing

Preheat oven to 400 degrees F.
Cook your potatoes and mash them, if you aren't using leftovers. While they are cooking, make the pastry dough by mixing the flour and salt with the butter, cutting the butter in, until you have cornmeal like texture. Add the water slowly, and make into a ball, being careful not to overwork the dough. Cover and chill while you work on the filling.
Saute the cabbage and onion in butter over medium high heat. Once it is softened remove and mix with the potatoes, cheese and seasonings.
Divide the dough into 6 equal portions and make into balls. Roll out into a circle, about 6 inches in diameter. Place about 1/2 filling into one half of the circle, and fold over into a crescent shape. Crimp the edges and place onto a greased or silicone lined cookie sheet. Repeat with the rest of the dough.
Mix up the egg wash and brush on each pastry. Sprinkle with seeds and bake in the oven until the tops are browned a bit.