Slice the Kielbasa into ¼-inch slices, but not all the way through, using chopsticks or skewers to prevent cutting through completely.

Slice sausage crosswise into 1-inch bite-sized pieces for a total of about 20 bites per ring, or 40 bites for both rings. Place the bites into a large bowl or onto a baking sheet.

In a small bowl, combine the mustard, apple cider vinegar, brown sugar, and Worcestershire sauce. Divide the mixture into two bowls.

To the first bowl of the mustard mixture, add the mayonnaise and stir to combine. Store the sauce in the refrigerator.

Pour or brush about half of the second bowl of mustard sauce over the Kielbasa bites, ensuring the sauce gets in between each cut section. Reserve the rest of the sauce for after cooking.

Arrange the Kielbasa bites in a single layer in the air fryer basket. Work in batches if necessary.

Air fry at 400°F for 7-9 minutes, or until browned, shaking the basket halfway through cooking.

Remove the bites from the air fryer and set them on a platter or baking sheet. Pour or brush the reserved mustard sauce over each.

Garnish with parsley (optional) and serve warm with the refrigerated mayonnaise-based dipping sauce.