Preheat oven to 350 degrees Fahrenheit. Line a baking sheet with nonstick foil or parchment paper, and spray with cooking spray.
Add all meatloaf ingredients to a large bowl. Use hands to combine, gently but thoroughly.
Place meatloaf mixture onto the tray and shape into a loaf shape (doesn't have to be perfect).
Bake for approximately 40 minutes, or until internal temp reaches 160F.
While meatloaf is baking, combine sauce ingredients in a small bowl.
To serve, cut meatloaf into slices and spoon the sauce over the top.
Notes
Ground turkey: I get the best results using 1 lb of extra lean (such as 97%-99 lean) turkey and ½ lb of lean (85% lean) turkey.
Celery: Mince the celery finely so you don't get large chunks of celery in your meatloaf.
Cajun seasonings can vary in spice. If you're worried about spice, you can simply look for a mild Cajun seasoning, or substitute some of the Cajun seasoning for sweet paprika.
If you have pre-made tartar sauce on hand, you can swap that for the mayonnaise and relish in this recipe (just use 3 tablespoons total)
If you don't have breadcrumbs available, you can use regular bread as a substitute. If it's stale bread, you can grate it into breadcrumbs. If it's fresh, use your hands to tear into small pieces.
If you own a food processor, you can use it to mince the vegetables quickly.
If you want to lighten things up even more, you can substitute low fat mayo or even Greek yogurt for the regular mayo in the sauce.