Place all the vegetables and chillies in a saucepan and cover them with water. No need to add the salt at this stage.
Bring it to a boil and lower the heat. Simmer for 10 minutes.
Carefully remove the vegetables and chillies from the water and place them in a blender. Add 4 tbsp of the water and the salt. Blend until smooth. Do not get rid of the water where you cooked them in case it is needed later.
Let it cool down. If it looks too thick, add a bit more of the water. It is perfect for any tacos, but I like to eat it with steak tacos.