Heat oven to 425ºF. Spread the fries on a baking sheet in a single layer and bake for 25 minutes, or until crisp and golden, turning them over halfway through.
In a mixing bowl, combine the lemon juice, 1 tablespoon olive oil, and garlic. Season with salt and pepper. Add the chicken, turning to coat. Let sit 10 minutes. Heat the remaining olive oil in a arge skillet. Add the chicken and saute 6-8 minutes, or until cooked through.
In a large bowl, combine the tomatoes, cucumber, bell pepper, onion, artichoke hearts, olives, and vinegar.
To serve, top the fries with the chicken, vegetables, and tzatziki sauce.