In a bowl whisk together 1/4 cup olive oil, lemon juice, vinegar, garlic, 2 tsp oregano, 1 tsp basil, the thyme, coriander and season with salt and pepper to taste (I used 3/4 tsp salt 1/4 tsp pepper).
Place chicken in a gallon size resealable bag, pour olive oil mixture over chicken and press chicken into marinade. Seal bag and refrigerate 45 minutes to 2 hours (no longer than 2 hours or the chicken will start to get mealy because of the acidic ingredients). If using wooden skewers soak them in water for 30 minutes.
Drizzle and toss veggies with 2 Tbsp of the olive oil (I just left them on the cutting board and tossed them) and season with remaining 1/2 tsp oregano, 1/2 tsp basil and salt to taste.
Preheat a grill over medium-high heat. Thread a red bell pepper, red onion, zucchini, 2 chicken pieces on to skewer and repeat twice.
Brush grill lightly with olive oil, place skewers on grill and grill until chicken registers 165°F (73°C) in center, about 8 - 12 minutes, rotating once halfway through cooking. Garnish with parsley, serve warm with tzatziki sauce.