In a medium bowl, dissolve 2 tablespoons salt in 1-quart cold water. Submerge chicken pieces in brine, cover, and refrigerate for 30 minutes.
While chicken is brining, prepare the sauce by combining oil, parsley, lemon zest, lemon juice, honey, oregano, and 1/2 teaspoon pepper in a medium bowl. Transfer 1/4 cup sauce mixture to a large bowl, and set it aside for later.
PREP & COOK CHICKEN:
Remove chicken from brine and pat dry. Toss chicken with remaining sauce mixture.
Preheat a large skillet over medium-high heat. Add the chicken and cook until cooked through and lightly browned, about 5-6 minutes. Add the onions and bell pepper to the skillet and cook until softened, 2-4 minutes.Take the skillet off of the heat and pour in the reserved sauce. Toss to combine and let the mixture sit for 5 minutes.
ASSEMBLE CHICKEN SOUVLAKI PITAS:
Lay a warmed pita on a 12-inch square of foil. Spread pita with about 2 tablespoons Tzatziki.
Place one-quarter of chicken and vegetables in the middle of each pita. Garnish with tomatoes and feta.
Roll pita to look like a cylinder. Repeat with remaining pitas and serve immediately.