Maybe Christina had grown to like it by then. I think the scene was supposed to show how controlling Joan was, ordering the food for her daughter even when she was clearly old enough to do it herself. And, of course, she ordered the steak the way she herself liked it.
Young children often don't like food they don't know. Many young children don't like asparagus, either. And Christina didn't seem to like the way the steak "bled" when she was trying to cut it. Cutting a steak isn't easy for young children, either. But Joan was often treating her children like adults, like expecting them to care for their clothes, or keeping the bathroom scrupulously clean.
I personally like rare or medium rare steaks, and I also eat steak tatar. My mother, on the other hand, doesn't like her steaks farther on the red side than medium, and she has never had a bite of steak tatar in her life. I told her that the taste is rather unique, but the closest it comes to is good butter.
You may cross-examine.

If that steak wasn't cooked to 145 degrees F it could have been dangerous.
At long last, the truth will OUT! Mommie was slowly trying to kill the kids with raw meat to collect the insurance money.!!
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^So true, I work as a chef! 145 is the rarest I will cook beef in an institution and I will NOT cook pork less than 165, even though 145 is now considered safe.
As for this movie, the steak on little Christina's plate looked almost raw and should have been more cooked. As for the meat ordered in the restaurant, probably a little more done.

If that steak wasn't cooked to 145 degrees F it could have been dangerous.

While making hamburgers, we ate the raw but that was a long time ago. The food production system is far different, hasty and may not have the best butchers hacking away at the carcass, avoiding opening up the intestines and all of the bacteria-ridden feces that spills out.
You are looking at a young girl who did not like rare steak. Often kids cannot eat a lot of heavy food let alone meat cooked in a away they do not like even if someone else who likes rare meat would love to have it.
She may have known about medium/well done because she lived in a sophisticated environment.
"Two more swords and I'll be Queen of the Monkey People." Roseanne

when i was a kid the first time i tried steak it was rare and i thought it was absolutely disgusting. so my mom cooked it medium well for me and i still hated steak. some people just think meat is gross. i have been a vegetarian for years now, and cant remember the last time i even ate chicken. rarer meat is very gross for many people, essp people who arent fans of meat in general.

I think it's natural to have an innate-dislike also, like cottage cheese

the weird thing I grew up on rare steak, hamburgers and roast beef. that was all we knew because of how my father liked his red meat. I am kind of surprised [and not believing] that Christina would dislike her steak rare [the way it was served to her]. how would she even know about medium/well done???
and she should have been happily freaking out at the steak when she was younger. that was black market steak and no one else [no normal people] were able to get steak.
Oh God. Fortune
vomits
on my eiderdown once more.