In a medium bowl, whisk together the oil, zest, lime juice, garlic, cumin, salt and pepper until thoroughly combined and smooth.
Add the chicken and toss until coated with the marinade.
Cover and refrigerate for at least 2 hours, or overnight.
Remove chicken from fridge.
Place a grill pan over medium-high heat and spray the grill lightly with cooking spray.
Remove the chicken from the marinade. Discard the marinade.
Grill the chicken about 5 minutes on each side, or until cooked through.
Remove from heat and set aside.
Place chopped lettuce on the bottom of a large salad bowl.
Arrange olives, tomatoes, prepared chicken and queso fresco over lettuce; set aside.