How would cooking change at 1km depth under sea? A chimpanzee has just returned to the surface after extended time at 1km depth, breathing trimix air. This brings the possibility of hyperbaric habitation, however how  would the basic functions of cooking be affected in hyperbaric conditions?
Specifically, could we have ice cubes or ice cream? Water boils at over 300°F, so no steaming anything - is steam cooking impossible? I know that tea pots and coffee pots would not work. Some things likely will also not evaporate.
This question mostly concerns hyperbaric consequences of food preparation that involves phase-changes.
The question is constrained to processes by appliances used in common residential kitchens to boil, broil, sear, fry, bake, chill, freeze, steep, brew, etc.
 A: Cooking under high pressure is totally possible, but some recipes would need to be changed.
Say the boiling point of water at this pressure is 150 C. That means boiling water will be far hotter than we are used to, and will cause more vigorous reactions and diffusion.
The most salient effect is that boiling water would be hot enough to cause the Maillard browning reaction: boiling would produce similar tastes to frying for meat and dumplings. Steamed buns would go brown.
Unfortunately this also means that food that gets its texture from steam bubbles (omelette?) would have to be heated far more than normal, likely making both texture and taste wrong (the egg proteins coagulate at 60-70C; heating the omelette enough to get steam would fry it to a rubbery mess, I think).
The bread in the oven would brown nicely but would have much impaired evaporation and would only fluff up because of CO2 bubbles from the yeast expanded: the result would be a soggy mess. Heating up further would cause sugar caramelisation around 160 C, which might change taste for normal bread a bit. Above that you will get pyrolysis and charring; it is quite possible that bread would easily end up too brown and charred yet still soggy.
Boiling water for tea would produce a too hot tea that would ruin the taste by dissolving a lot of bitter stuff quickly. The same goes for coffee.
Freezers would work as normal, and at this pressure ice formation is roughly normal.
Carbonated beverages from the surface would on the other hand be rather disappointing, since they would lack much fizz.
