Slice each breast (20 oz in total) open, but not all the way through, to create little pockets.
Season the chicken with 1 1/2 tbsp olive oil, 1 tbsp Italian seasoning, 1 tbsp cayenne, 2 tsp paprika, 1 tsp Dijon mustard, 1/2 tbsp onion powder, 1/2 tbsp garlic powder, 1/2 tsp salt, 1/2 tsp ground black pepper, 1/2 tsp fresh thyme, 1/2 tsp dried oregano, and 1/2 tsp Cajun seasoning. Season both the outside and inside of the chicken.
Arrange the seasoned chicken in the air fryer along with 2 oz of lemon slices. Cook at 400°F for 20 minutes.
Meanwhile, prepare the salad dressing by combining 2 tbsp Greek yogurt, 2 tbsp Japanese mayonnaise, and 1 tbsp olive oil. Place in the fridge.
To serve, toss the vegetables (4 oz lettuce, 4 oz cucumber, and 0.5 oz radish) with the dressing. Pull the chicken out, plate it, sprinkle with parsley, and enjoy with the side salad.