Something I have noticed about Sous Vide that differs from traditional cooking methods: The meat color seems to be more red than we are used to in judging the doneness.
So - medium rare - stricly looking at the color - will appear to be more like a rare steak in
color only. But the texture will be firm like med-rare. So, it is one of those occasions where "The eye should NOT take the first bite".
Otherwise - you will get complaints of "It looks raw".
I have not read this anywhere yet - so it is my own presumption that when SV cooking to anything less than well done ( and if I am wrong - please correct/educate me) we cook at such significantly lower temps, that the myoglobins (which are naturally bright red) that are present throughout the muscle are not displaced by high heat at the surface of the meat as in "grilling" - so the water/fluids/myoglobins can remain where they naturally occur in the meat.
The result is more taste and moisture retention. But the "side effect" is that because the naturally red myoglobins are not driven out of their normal dispersement throughout the meat - even a medium rare steak or roast will not have the red juices like a traditionally cooked ( hot grill )steak. The juices will be almost clear - to clear.
I say all of this because - well....the Mrs. T was a WELL DONE
steak person when I met her...and I have slowly converted her to medium-rare. But, the first SV cooks - I had to convince her to try it - because her eyes told her that the color of the meat meant it was way under cooked. Once she took a bite or two - she was convinced tho.