Blot the chicken dry with a paper towel. Sprinkle on the blackening seasoning, pressing to ensure the seasoning adheres and the chicken is thoroughly coated.
Heat the oil in a cast-iron skillet over medium-high heat. You will want to turn on a fan, this dish will smoke. Add the chicken and cook for 5 minutes. Flip and cook for another 3 to 5 minutes, or until the chicken reaches about 155 F.
Top each chicken cutlet with salami and cheese. Allow the cheese to melt while the chicken finishes cooking.
Move the chicken to a platter and allow it to rest while you toast your buns cut side down in the pan for 2 to 3 minutes.
To assemble, slather your buns with the spicy mayo, add the chicken and then top with the lettuce, tomato, and onion.
Whisk together all the ingredients in a small bowl. Season to taste with extra hot sauce.
If you can't find chicken cutlets substitute chicken breast and fillet it into a cutlet. Start by gently holding it in place with your hand flattened on top. Use a knife to carefully slice it in half horizontally.
If you use store-bought blackening or cajun seasoning be sure to check that it contains salt. If not, you will need to add salt when seasoning your chicken.