Chop the tomatoes as fine as possible, you could opt to remove the skin, but 1. it's a right pain, and 2 there are antioxidants in the skin.
Once chopped place in a sieve and sprinkle the salt over the top and leave to stand for 20 minutes.
De-seed the peppers and chillies, then chop them as fine as you can manage.
Chop the onion and garlic into small pieces also.
Add the oil to a pan and heat.
Add all of the ingredients and bring to the boil, then simmer for 5 minutes, stirring continuously.
Remove from heat and move to containers.
This recipe makes a decent amount of salsa, save some to use, freeze the rest.