Combine mint, lemon peel, 2 tsp of the lemon juice, olive oil, 1/4 tsp of the salt, and 1/8 tsp of the pepper in a bowl and set aside.
Bring 4 cups salted water to a boil.
Prepare tzatziki sauce by peeling and grating half of the cucumber. Cut the remaining half into bite sized pieces and set aside. Squeeze the grated cucumber to remove excess water. Combine the grated cucumber, yogurt, remaining 2 tsp lemon juice, 1 tsp of the garlic and 1/4 tsp salt in a bowl and set aside.
Halve any large chicken tenders and combine them in a bowl with the cornstarch, 1 Tbsp of the dry sherry, remaining 2 tsp garlic, remaining 1/2 tsp salt and remaining 1/8 tsp pepper. Stir until the cornstarch is no longer visible. Stir in 1 Tbsp of the vegetable oil and set aside.
Heat a 12 inch stainless steel skillet over high heat until a bead of water evaporates within 2 seconds. Add the orzo and cook, stirring constantly for 1 - 2 minutes to toast it. Transfer the orzo to the boiling water and cook for 9 minutes or until tender. Drain and set aside.
Meanwhile, add the remaining 1 Tbsp of oil to the pan. Add the chicken, spreading evenly in a single layer. Cook, undisturbed for 1 minutes until the chicken begins to sear. Stir-fry 1 minute or until chicken is just opaque. Swirl in the remaining 2 Tbsp dry sherry and stir-fry another 1 - 2 minutes until the chicken is cooked through. Add the tomato quarters and stir-fry for 30 seconds. Remove the pan from the heat. Stir in the cooked orzo and cucumber pieces.
Drizzle the chicken and orzo with the mint mixture. Serve with tzatziki sauce.