If you have a mister, lightly spray the diced avocado with a little bit of additional lemon or lime juice to prevent them from browning.
In a large mixing bowl, add the tomatoes, red onion, avocado, cucumber, and cilantro.
Mix together the olive oil and lemon or lime juice in a small bowl, drizzle over the salad and gently toss together to mix. Cover and place in the fridge.
When ready to serve, gently toss the salad with the salt and pepper, enjoy.