Roughly chop all the vegetables. Cut the slower cooking vegetables into slightly smaller pieces than the faster cooking ones.
Heat the oil in a large wide pan and add in the vegetables and salt and cook on medium-high heat. As the vegetables release their juices, turn up the heat and cook until the water has evaporated by at least half and all the vegetables are soft. Add in the fresh herbs and cook for a minute more.
Blitz it all up in a blender until smooth. Pour into steralised jars.