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

Spread the chicken and lemon slices onto a sheet pan in a single layer. Roast for 15 minutes, then toss and return to oven for an additional 4-7 minutes, until caramelized and cooked through.

In a medium bowl, whisk together plain yogurt, dill, parsley, chives, lemon juice, olive oil, and a pinch of salt until smooth. Fold in shredded cabbage and let sit for 10-15 minutes.

Warm pitas in a skillet or foil. Fill each pita with slaw, roasted chicken, and avocado. Serve warm.