Preheat a grill (or skillet/oven safe pan over medium heat, preheat the oven to 350°F).
For the aioli: Whisk together mayo, lime juice, chili powder, garlic powder, and scallions. Season with salt and pepper to taste and set aside.
Season ground turkey with Worcestershire sauce, garlic powder, Cajun seasoning, salt and pepper. Use your hands to form the mixture into equal patties.
Place the burgers on the grill and cook on both sides to an internal temperature of 160°F using a thermometer. Also, grill the onion slices until somewhat charred and soft. (If using a skillet, lightly grease the pan with 1-2 teaspoons of oil and sear the burgers on both sides to golden brown. Transfer the pan to the oven and continue cooking to an internal temperature of 160°F using a thermometer). When the burger is close to done, melt the cheese over top.
Toast the buns golden brown. Spread the aioli on the bun or serve it on the side if desired.
Layer the bun with lettuce, the burger topped with onion, and tomato seasoned with salt and pepper. Serve with pickles and chips.