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Bring 2 US qt (1.9 l) or more of salted water to a boil. Heat 0.25  c (59 ml) of butter and/or oil in a large skillet.
Pour the water into a large pot and place it over high heat on the stove. Add a heavy pinch of salt to the water as it comes to a boil. Use 2 US qt (1.9 l) of water for every 8-10 pierogies—roughly 12–16 oz (340–450 g). Place the skillet over medium heat and add butter, olive oil, or a combination of the two. Preheat the pan and oil for 2-3 minutes. This amount of oil is sufficient for 16 oz (450 g) of pierogies (about 12 pierogies).