I read that garlic pressed hard by the back of a knife releases oils, but then some recipes just say to chop. Are there any preferred ways or does it depend on the dish being cooked?
Crushing with the flat of your knife also makes it super easy to peel. I always crush-peel-chop. This way you'll also get the most garlicky taste and aromatics. Since the compound allicin, which is responsible for that spicy fragrant garlic taste, is created when the garlics flesh is torn.
I love this article from Serious Eats about different ways to chop garlic.
The summary of it is that the more cell walls you rupture, the more strong and acrid the garlic taste is. A microplate is at the far end of that spectrum, but crushing the garlic also releases this extra garlicky power.
Too much of this can be overwhelming in a dish, so there are times when finely sliced or diced but not crushed is preferable. The deciding factor seems to be how you plan to cook it; long cooking rounds out the garlic flavour so by the end, it doesn't seem as important whether it was diced or crushed. Also, there are some instances where one might want the sharper garlic taste.
In my experience, which is by no means gourmet, there are reasons for both. Sometimes the need gor the garlic is to add a flavor without being explicitly consumed - not quite a tadka, but cooking in oil to release flavors. In those cases presentation comes into play too - sliced fried garlic as garnish, versus crushed and chopped/minced garlic as a cooked-in component.
Many times, I personally cannot be arsed to do garnishes for a dish I am making for flavor cravings, so I fire the garlic in minced. There's, like, a very few Chinese dishes I've had that use the garlic in the cooking but not intended for consumption so in it goes, regardless of whether or not it's supposed to be included.
I usually use a garlic press because I don't find that the extra time I use cutting the garlic adds any different flavour. Though, sometimes I do chop it up if I am frying since I love crispy garlic.
Exactly this and for that reason. If it's minced you always have to chop.. there almost never a reason to skip one or the other. And the exceptions like spaghetti with garlic need carefully sliced garlic. Mmm so good.