I have been told it's a bad idea to put vegetables directly in hot or boiling water when cooking minestrone. Instead, you must start heating the chopped vegetable soup from cold water. Why would this be?
Looking at the Giallo Zafferano recipe (video below), this does seem to be the case.
According to the Farmers Almanac, root vegetables (potatoes, carrots, anything that grows underground) benefit from the cold water technique as the cell wall gradually stiffens and it helps the vegetables become more resistant to overcooking. Adding directly to boiling water could (in theory) affect the consistency and flavour of the broth. In a similar way, if you pre-soak vegetables some starch and proteins are released into the water beforehand, and if you don't use that soaking water, there will be less starch and foam when the stock comes to a boil.
In reality though, the difference would probably be fairly negligible, especially if you are in the habit of removing any scum that forms when the liquid comes to a boil.
Giallo Zafferano: https://youtu.be/JEtJz-_oBVk