This is the classic salsa of Tex-Mex cooking, often used as a dip for corn chips and nearly always a real horror, particularly anything that comes in a jar. Fortunately it is remarkably easy and quick to make, so there is really no need to ever suffer a bad one again.
Combine all the ingredients in a suitably sized bowl. Please do not be mean with the salt as this is what creates the salsa by drawing flavour and moisture out of the other elements. Leave to marinate for about an hour to allow the salt to do its work.