When I am cooking small pieces of meat (so a meat thermometer is not an appropriate tool – I'm thinking of things like shredded chicken being stir-fried, frying or grilling slices of bacon, or minced beef being browned in a pan) I tell whether it is cooked yet by the change in colour in the meat. Chicken goes pink -> creamy white, bacon goes pink -> a different shade of pink, beef goes reddish pink -> brown, etc.
How does a blind, or colour-blind, chef manage? If going purely by time of cooking you will surely either end up with some pieces undercooked or the whole lot overcooked to compensate for that. Also it depends so much on the exact size of the pieces of meat, in the case of a grill how close the meat is to the heat, etc.
This is not a purely theoretical question – my husband is colour blind and really struggles with this. He cannot see the relevant colour differences at all, and although there are some texture changes on the outside of the meat, that doesn't tell you that the pieces are cooked all the way through.
Best Answer
Texture. Although I can see perfectly, I use texture to tell me if pasta is done, for example. It's obvious for spaghetti but I do it for macaroni too, or any shapes. Just stirring a pot full of boiling water with raw macaroni, then stirring a pot full of boiling water and cooked macaroni, is a very different experience. Stir frying raw meat, partly cooked meat, and cooked meat will also feel different. Grilling meat is definitely a time for everyone to use texture, probably some variant of the press-the-ball-of-your-thumb rule.
To a lesser extent, smell. This is what I rely on to evaluate baked and roasted things, long before I open the oven to look at them or touch them. It won't help you grill a steak though.
FYI, I asked Christine Ha on Twitter, and she replied
Which is as close to "from the horse's mouth" as it seems we will get in this thread.