If you are not down with the coffee terminology, this [1] is a good explanation of what "the bloom" means.
Basically it's a thing that forms when fresh coffee grounds get moist, since that accelerates the release of trapped gasses. The gas leaves the grounds, but gets trapped by the surrounding water and substances extracted from the coffee, forming a foam.
My interpretation is that "puncture the bloom" basically means "stir to break the formation of a foam ball on top of the coffee grounds".
Yes, the bloom is the foam that forms in the coffee grounds. It’s CO2 and releasing it allows for better extraction.
Puncture means to take a knife and cut a few pie slices into the mass of grounds and release the gas beneath. The grounds will sink at that point. I try not to stir aggressively since that is counterproductive to producing a “clear” cup.
Once a few minutes have passed, you can plunge accordingly.
I never knew what the bloom was, but I blindly followed directions from smart people on using the french press. Pour the 90C water into the pot, wait a minute, then stir the beans down into the water. Wait a few minutes more. I usually do 1min+4min.
Here’s a thing to try. Pour in the water about half way. Give it a quick stir. Let it sit for 45 seconds and then slowly pour in the rest of the water. Let it sit for 4 minutes. Then puncture the grounds in a couple places. Wait another 2 minutes and then plunge.
Basically it's a thing that forms when fresh coffee grounds get moist, since that accelerates the release of trapped gasses. The gas leaves the grounds, but gets trapped by the surrounding water and substances extracted from the coffee, forming a foam.
My interpretation is that "puncture the bloom" basically means "stir to break the formation of a foam ball on top of the coffee grounds".
[1] https://foodal.com/drinks-2/coffee/guides-coffee/what-is-blo...