I've been coooking soup with a pot lid off and notice the meat is still tough when cooking. It could be the due to the lid or some other factor.
I put a thermometer in the soup water and it seems to be at a good temp for simmering meat(90-95c) and I can see the bubbles appearing every seconds or so. However the meat is still tough.
I put the lid back on and cook then it seems to soften ok. Considering I can see the simmering bubbles and the thermometer shows a simmer can you explain why and if putting the lid on is making a difference?