To cook potatoes evenly, drop in cool
water, not hot. Hot water will make the outsides mushy and not cook
the insides evenly. Allowing to water to warm up with the potatoes
cooks the outside and inside evenly. Potatoes are more dense than
veggies.
Heat the pan before cooking veggies. Preheating the pan and using a
bit of olive oil keeps the veggies from sticking and helps them
evenly brown without making them mushy.
Meat should never be tossed into a cold pan, in the oven or on the
stovetop.
Slicing onions vertically is to slice along with the fibers of the
onion. When you slice with the fibers, the onion pieces hold up a
bit better as they cook. If you do not want them to retain the
shape, cut along the side like circles or dice them and they will be
more mushy.
Cakes should be light and airy and one way to help is to alternately
mix in dry and wet ingredients. It is bubbles, unpopped and whole,
that give an open crumb in cakes. When you are beating sugar into
softened butter or when you are beating eggs into a froth, you are
making bubbles. Adding dry ingredients keeps the bubbles from
popping and makes for a light, airy cake. Dump and stir is better
for more dense things, like brownies.