In a deep frying pan, sauté onion in oil over medium heat for about 15 minutes, or until it starts to turn slightly brown. Add shredded chicken and mix periodically until it begins to get crispy, about 10 minutes. Add the packet of taco seasoning and 1/4 cup water. Mix thoroughly.

Make the salad dressing by mixing the olive oil, lemon juice, salt, and pepper. Toss with the lettuce, tomato, and cucumber.

Follow package instructions to warm the taco shell. Layer shell first with cooked rice, then chicken, then salad. Top with salsa if desired, and enjoy!