Place the chicken breasts between two sheets of plastic wrap and flatten with a rolling pin to thickness of about ½ inch.
Finely chop 1 tsp of the cilantro and combine in a shallow bowl with, garlic, oil, salt, and pepper. Coat the chicken in this mixture and marinade about 15 minutes, turning once. Chop remaining cilantro and mix with yogurt. Set aside a few leaves for garnish.
Pre-heat a griddle pan or broiler until hot then cook the chicken for 3-4 minutes on each side or until browned and cooked through.
Mix about half the cilantro with the yogurt
Slice the chicken and serve with a salad of arugula leaves. Top with yogurt and garnish with remaining cilantro leaves.