- Using a food processor,* chop garlic. Add basil, coriander, mint, olive oil, lemon juice, pepper and salt.
- Process until smooth. Reserve 60 mL (1/4 cup) of the herb mixture. Preheat barbecue at medium-high heat.
- Brush chicken breasts generously with herb mixture. Place meat on the barbecue and grill, covered, for about 7 minutes on each side, or until cooked through and no longer pinkish inside.
- Brush chicken with herb mixture during cooking. Remove cooked chicken from heat and cover with aluminum foil. Allow to sit for 10 minutes. Slice chicken into strips.
- Spread remaining herb mixture onto half of each ciabatta. Arrange chicken strips and tomatoes on top.
- Season with salt and pepper to taste. Spread remaining ciabatta halves with tzatziki and close sandwiches.
* If you do not have a food processor, you can use a hand blender or a knife. The mixture will be coarser.