Cut each breast piece horizontally as even as possible- you end up with 2 fillet from each breast piece of equal thickness.
With a meat mallet or with anything heavy, pound the chicken gently (focusing on the thicker end) so that the chicken fillet is of equal thickness. This ensures even and quick cooking.
Mix the ingredients mentioned under the marination heading- yogurt, dijon mustard, salt, ginger-garlic paste, red chili flakes, black pepper powder, cajun seasoning and vinegar.
Place all the chicken fillets in the marinade and coat it well. Leave it to marinate for at least 30 minutes.
Stovetop Cooking: In a non-stick frying pan on medium-high heat, add 2-3 tablespoons of oil. Add the fillets. Cook in batches, do not overcrowd it.
Cover and cook for at least 5 minutes (it will help develop a nice golder crust). Then flip, cover and cook the other side for around 5 minutes. Depending on the thickness of the fillet, total cooking time will vary between 8-10 minutes per fillet.
Air fryer method: Place fillet in the airfryer without overcrowding and air fry at 390F for total 10-12 minutes (6 minutes per side).
Once done, remove the fillet, place in a bowl and cover immediately.