Wash all vegetables thoroughly.
Slice cucumbers thinly, about 1/4 inch thick.
Halve the cherry tomatoes.
Dice the avocados: cut in half, remove the pit, score the flesh in a grid pattern, then scoop out with a spoon.
Thinly slice the red onion.
In a large bowl, combine cucumbers, tomatoes, avocados, and red onion.
Add chopped cilantro.
In a small bowl, whisk together olive oil and lemon juice to make the dressing.
Pour the dressing over the salad and gently toss to combine.
Season with salt and pepper to taste.
Serve immediately or chill for 15-30 minutes for a cooler salad.