You need theml mtsl clips in order to achieve the vaccum. Bormioli Fido and Weck jars have been tested to be effective (YMMV) . What the inventor says is that is not really the metal but also its shape that breaks thwle microwave, after all my own microwave came with a metallic gadget to keep the dish near the grill.
My microwave broke probably for a combination of metal and some food stain on the metal parts of the jar, that is my gut feeling as well.
I am not really advising people to try, but it's a such interesting method that I am finding videos from actual chefs about it.
A similar way of unsupervised but likely slower and less reproducible cooking would be to submerge the jar(s) in a pot full of water and let them sit there for a while. The advantages being able to overcook things (e.g. the meat) if you want to and not risking breaking anything. You would consume more energy though.
My microwave broke probably for a combination of metal and some food stain on the metal parts of the jar, that is my gut feeling as well.
I am not really advising people to try, but it's a such interesting method that I am finding videos from actual chefs about it.
A similar way of unsupervised but likely slower and less reproducible cooking would be to submerge the jar(s) in a pot full of water and let them sit there for a while. The advantages being able to overcook things (e.g. the meat) if you want to and not risking breaking anything. You would consume more energy though.