For the Chicken: Combine yogurt, spices, lemon juice, olive oil and salt and mix until combined. Add chicken to the yogurt mixture and marinade for at least 30 minutes, up to overnight. Place chicken on bamboo skewers that have been soaked in water. Grill over medium-low heat for 20-25 minutes or until cooked through. For the Sauce: Combine all sauce ingredients in a medium sized bowl and refrigerate until ready to use. To Assemble: Chop vegetables and arrange on a plate. Lay cooked chicken skewers over the salad and top with the tzatziki sauce and a drizzle of olive oil.