In a small bowl, combine garlic, paprika, thyme, ground coriander seeds, red pepper flakes, salt, pepper, lemon juice, lemon zest, and oil. Stir until combined.
Cut chicken thighs into thin strips. Transfer to a gallon size zip-bag or bowl. Add marinade to chicken and mix well, making sure all pieces are coated. Cover and marinate at least 30 minutes in refrigerator.
Heat a large nonstick skillet over medium high heat. Add chicken in two batches and saute 4-5 minutes, or until cooked through.
To make the fries, preheat oven 450°F. Place cut potatoes on a parchment lined baking tray. Drizzle with oil, and mix to combine. Spread fries in a single layer and cook 12 minutes. Flip fries and cook an additional 12-15 minutes. Remove from oven and sprinkle with salt.
To assemble the chicken gyro platters, place mixed greens, tomatoes, and onions on plate. Add cooked chicken, fries, Greek yogurt, and whole wheat pita bread.