Hey all, need to cook some red meat at 70C due to a certain someone being with child. She has been advised meat needs to be cooked at this temp while pregnant. Who am I to argue? 
I assume I can just up the temp to this and cook it the same time and itāll be āwell doneā. I also assume I can pull the other meat out at, say 45 mins, for a less cooked version. Oh and itāll be rump steak and about an inch thick.
Any other options?
Cheers
Actually, Iād cook hers first. Then let the bath cool down to your lower temp and drop the other steaks in.
The extra time wonāt make the well done steak any tougher - and keep them all warm, so you can finish them all together.
Also, the time - you really donāt want to shorten your time to produce a āless doneā version - thatās what temperatureās for. If anything, taking things out early will result in uneven cooking. Not a desirable result.
Iād likely be cooking them for an hour at least.
If you havenāt seen them, the steak guide over on serious eats and the information (including thickness guidelines) over at Douglas Baldwinās site have a plethora of information on making the perfect steak. 
If she is normally a medium rare person, Sous Vide can pasteurize at lower temps. Traditional methods, yea, it needs cooked well done for pregnant/compromised immune systems, but sous vide can provide the same level of pasteurization just over a longer period of time. So a steak that reaches 70C is immediately pasteurized, but the same steak cooked to 55C and held for the 3 hours is also pasteurized!