Here’s the part nobody wants to hear: Patience is a non-negotiable ingredient. You bring everything to a boil, then you drop it to a bare simmer. If you boil it hard, the broth turns cloudy and greasy. That’s a crime.
You let it go for at least 4 to 6 hours. Some restaurants simmer for 12 hours or more. You skim off the scum (that gray foam) every 30 minutes like it’s your job. It’s tedious, but a clear broth is a beautiful thing.
How to Make Pho Soup Broth: The Base of Authentic Vietnamese Flavour