Wash and dry all produce.Lightly oil the grill.While you prep, preheat the grill to 500°F over medium-high heat. Cut cucumber into 1/4-inch rounds.Cut tomato into 1/2-inch pieces.Roughly chop olives.Halve ciabatta buns. Peel, then mince or grate garlic. Combine garlic and 1 tbsp (2 tbsp) oil in a small bowl. Brush garlic oil over cut sides of ciabatta buns. Set aside.

Pat chicken dry with paper towels. Add chicken, 1 tbsp (2 tbsp) oil and Mediterranean Spice Blend to a medium bowl. Season with salt and pepper, then toss to coat.Add chicken to one side of the grill. Close lid and grill, flipping once, until cooked through, 4-6 min per side.** Transfer pork to a plate. Cover with foil to keep warm.

When chicken is almost done, add ciabatta buns to the other side of the grill, cut-side down. Close lid and grill buns until toasted, 2-3 min. (TIP: Keep an eye on buns so they don't burn!)

When chicken is done and resting, add vinegar, 2 tbsp (4 tbsp) oil and 1/4 tsp (1/2 tsp) sugar to a large bowl. Season with salt and pepper, then whisk to combine. Cut or tear ciabatta into 1/2-inch pieces. Add cucumber, spring mix, ciabatta, tomatoes, olives and feta to bowl with dressing. Toss to combine.

Divide chicken and salad between plates. Dollop yogurt sauce over chicken.