Leftover management: piroshki

I made half of Michael's recipe for braised pork shoulder, and I liked it a lot, the melt-in-your-mouth texture, the perfectly balanced taste, the aroma of the pork roasting with the spices spreading through the house. And the price. Pork shoulder is one of the cheapest cuts of meat you can get in the supermarket.

The problem is, it's a restaurant recipe, and even half of it gave me way too much of braised pork. We ate it for dinner for a couple of days, then R. got a large piece of pork, browned on all sides, with his eggs for breakfast, then I mushed it into rillettes and we ate it spread on toasts as a part of our late-night wine and cheese plate, and there was still a lot left.
Finally I mixed what was left with some rice and sauteed onions and baked it into piroshki. Piroshki can be eaten in place bread, and they go well with a soup. Or they make a very good portable snack - take them to the office for lunch, on a day sail, or put them in your backpack and hit the slopes.
Last week I made a puree soup of the vegetables from the farmers market - baby leeks, parsnips, celery root - and my pork and rice piroshki went very well with it.

My favourite piroshki dough:

1 cup warm milk (body tempetature)
2-1/2 tsp dry yeast
1 tsp sugar
2-1/2 cups bread flour + more for dusting
2 Tbsp softened butter
1 egg
1/2 tsp salt

Egg wash:
1 egg
2 Tbsp water

Mix the yeast with 1/2 cup of milk and the sugar. Let sit for 20-30 minutes.
In a large glass bowl, combine 1 cup flour with the remaining milk and the milk/yeast/sugar mixture. Mix well. Cover with a clean napkin and put in a warm place until it doubles in size, for about 1 hour. Add the remaining flour, butter, egg and salt. Knead for about 5 minutes, rubbing your hand with some flour if the dough sticks to your hands.

Form the dough into a ball, put in a large glass bowl, dust with flour, cover with a napkin, and keep in a warm place until it doubles in size, 1to 1-1/2 hours.

Place the dough on a floured surface, roll out into a long log shape, and divide into 16 equal portions. Work with one portion at a time, covering the rest with a napkin to prevent drying.
Form the dough into a ball, roll out into a flat circle, place about 1 Tbsp of filling in the center and pinch the edges close. Place on a buttered cookie sheet. Repeat until you run out of the dough or filling (there is always something left over)

Prepare the egg wash: beat together the egg and water.

Brush the piroshki with the egg wash. Bake at 375 degrees until golden, about 20 minutes.
Let cool before serving.

The filling could be:
- braised or boiled beef, pork, or chicken, shredded + sauteed onions + (optional) rice or buckwheat
- steamed or boiled cabbage, spinach, kale + sauteed onions + (optional) chopped hard boiled egg
- cooked fish + rice
- sauteed mushrooms
- anything