Add prepared red onions, radishes, green and red bell peppers, leeks, zucchini, and flat-leaf parsley into a large mixing bowl.
Spoon in vegan or non-vegan mayo, sea salt or kosher salt, freshly cracked black peppercorns and Old Bay seasoning. 
Add the chopped rotisserie chicken breasts.
Fold ingredients gently until the mixture is thoroughly combined. 
Serve with crackers, toasted baguette rounds, or bagel chips.