I have to admit that I always make my salads by eye, making up the amount that looks right to me at the time.
For this salad I use roughly:
6-8 vine tomatoes (if you can get them)
One Red pepper ( the sweet type that are sometimes called bell peppers)
One yellow pepper
one small red onion
2 cloves of garlic
a generous bunch of fresh coriander leaves
virgin olive oil
Remember that you can adapt the amount of ingredients to suit your needs, but this is my basic ratio.
So for this salad I slice the tomatoes into sixths or eighths depending on size, taking out the hard little bit and then dice them. Then slice and dice the peppers into a similar size.
Finely chop the small red onion and crush the garlic.
Once all these ingredients are in your bowl, thoroughly wash the coriander and then chop it or cut it with kitchen scissors and add it.
Now all you have left to do is season to taste using the virgin olive oil, salt and pepper.