(My mother’s “recipe”. This is perfect as a substantial appetizer/salad and also works as a palate cleanser. The sweetness of the apple makes the tomato and cucumber seem almost salty, even as everything remains crisp and light.)
Chop roughly equal amounts of red apple, tomato, and cucumber into small cubes. Squeeze half a lime onto the apple cubes to prevent browning, before tossing everything together.
You could add seasoning with mint or a hint of salt, but it really doesn’t need it.