In a large bowl, combine the lemon zest and juice, garlic, oregano, 2 tablespoons of the oil, ½ teaspoon salt, and ¼ teaspoon pepper. Add the chicken, cover, and let marinate for 30 minutes.
Cook the lima beans according to the package directions; let cool. Toss the lima beans with the Feta, shallot, the remaining 3 tablespoons of oil, ¼ teaspoon salt, and ¼ teaspoon pepper; set aside.
Heat grill to medium. Grill the chicken over medium heat until cooked through, 25 to 35 minutes. Serve with the lima bean salad.