In a large bowl, mix flour, salt, and spices.

Add egg, sour cream, oil, and warm water gradually. Mix until a shaggy dough forms.

Knead on a lightly floured surface for about 5–7 minutes, until smooth and elastic.

Wrap the dough tightly in plastic and let it rest at room temperature for at least 45 minutes (or up to 24 hours in the fridge). This step is key—resting relaxes the gluten, making the dough easier to roll.

In a skillet, sauté the chopped onion in a little oil until soft and golden.

Add garlic and cook 1 minute more.

Let cool slightly, then mix with the kielbasa (removed from casing).

Add marjoram, mustard, and parsley. Taste and season with salt & pepper.

Fold in the cream cheese to bind the sausage filling.

Roll out the dough to about 1/8-inch thick

Cut circles (about 3 inches across).

Place a spoonful of filling in the center of each.

Fold over, seal edges well (use water if needed), and crimp with fingers or a fork.

Bring a large pot of salted water to a gentle boil.

Boil pierogi in batches—when they float, cook 1–2 minutes more.

Optional: pan-fry in butter with onions until golden after boiling.