Preheat your oven to 425°F (220°C). In a large bowl, combine the boneless chicken breasts with brown sugar, smoked paprika, garlic powder, onion powder, cayenne pepper, kosher salt, and olive oil. Toss until the chicken is well coated. Add lemon slices on top of the chicken.

Spread the seasoned chicken and lemon slices on a large sheet pan in a single layer. Roast in the preheated oven for 15 minutes. After that, toss the chicken for even caramelization and return it to the oven for an additional 4-7 minutes, until golden brown and cooked through.

While the chicken is roasting, prepare the herby slaw by whisking together plain yogurt, minced dill, parsley, chives, lemon juice, olive oil, and a pinch of salt. Fold in the finely shredded green cabbage until well mixed, allowing to rest for 10-15 minutes.

When the chicken is done roasting and the herby slaw has rested, warm the pita bread in the oven. Open each pita pocket and fill them with a layer of herby slaw, followed by the roasted chicken and cubed avocado. Serve immediately.