Step 1

Cook vegetables: Melt 2 teaspoons of butter in a large nonstick or seasoned skillet over medium heat (see note 4). Add onion, cook until translucent, 2 to 3 minutes. Add bell peppers, cook, stirring occasionally until they begin to soften, 3 to 4 minutes. Season with salt and black pepper.

Step 2

Add sausage: Push the vegetables to the edges of the skillet, then add sausages in the middle. Cook, until the sausages are golden brown all over, 5 to 6 minutes (during this time, be sure to also stir the onions and peppers around too, so they brown evenly). Transfer the onion, bell peppers, and sausage to a plate and set aside.

Step 3

Cook pierogi (see note 3): Return the skillet to the stove over medium heat and melt the remaining 2 teaspoons of butter. Arrange the pierogi in a single layer in the pan. Cook, flipping occasionally, until golden brown on both sides and warmed through, 6 to 8 minutes. (You may wish to cover the skillet with a lid and add a splash of water to help steam the pierogi and cook them faster).

Step 4

Combine and serve: Cut the sausage into coins (about ½-inch thick). Add the sliced sausage, onions, and bell peppers back to the pan. Toss to combine. Cook for another 1 to 2 minutes to warm. Season with more salt if needed. Divide onto plates and serve with a dollop of sour cream (if using).