Cook bacon in a skillet over medium heat until crispy, about 8-10 minutes. Drain on paper towels and crumble once cooled.
In a large mixing bowl, whisk together mayonnaise, apple cider vinegar, sugar, salt, and pepper until smooth.
Add thawed peas, crumbled bacon, diced cheddar cheese, and red onion to the bowl with the dressing.
Gently fold everything together until well coated with the dressing.
Cover and refrigerate for at least 2 hours or overnight to let the flavors meld together. Give it a quick stir before serving.