Place frozen pierogies at the bottom of the air fryer basket. They can be touching but make sure they aren't overlapping. Lightly brush each pierogie with olive oil.
Cook the frozen pierogies for 10 minutes. At 5 minutes, flip the pierogies over to help them cook evenly.
While the pierogies cook, sauté the vegetables and sliced kielbasa. On medium heat in a medium sized frying pan, heat olive oil. Sauté the onions and sliced kielbasa for 3-5 minutes. Add the bell peppers and sauté until the onions are translucent and the bell peppers are tender yet crisp.
Whisk together the olive oil, red wine vinegar, and whole grain mustard.
In a baking pan or large platter, toss the sautéed vegetables, pierogies and kielbasa together and pour and the whole-grain mustard vinaigrette over the dish. Enjoy!
Notes
Spicy - add chili pepper flakes while cooking to add heat into the dish, or banana peppers
Deluxe - use kielbasa that has cheese inside of it for more flavor.
Kid friendly - serve the dish with pierogies, kielbasa, and sautéed vegetables in three different serving dishes so kids can assemble their own dish based on personal taste.
Add the peppers at the end of sauteing so they remain crisp.
If you don't like the texture of the air fryer pierogies, boil them instead.