I don't have a scientific backing to what I am going to say, but still I will try to make my point clear!
Cooking eggs is more of an intuitive thing. The fast vs. slow thing comes more from your own rendezvous with it.
Like in my house, when we say omelet, only my husband is allowed to put hands on it because he gets that perfect round thing without breaking any of the edges every single time he does it. I will share his method:
Take a flat pan and heat it good enough.
Drizzle a little oil on it and rotate the pan once so that oil gets to the sides.
Now all you need to do is pour your beaten eggs on the pan and slowly cook it on a low flame until the edges start separating from the pan automatically(atleast it will come out easily when you raise it with spatula)
And bang on, our omlete gets cooked pretty fine everytime with a very soft and fluffy texture.
But when you say scrambled eggs, I would follow a different methodology in which I would:
- Take a pan with deep base and heat it good enough.
- Pour very little oil, just so that eggs don't stick to the pan.
- Pour the egg mix and keep the pan on very high flame and stir the thing vigorously until the eggs are cooked and it looks ready.
Basically what I think is, when you cook anything on a high flame, you need to stir it along so that the food does not stick to the bottom and gets burnt(even when you are using a non stick pan, eggs might get stuck in a minute or so), which you can do while making scrambled eggs but can't do while making an omelet obviously.
I hope next time you put your hands on it, you will listen to your heart!! Happy Eggs!! :)
Temperature is the only foolproof way to determine doneness. Unfortunately it's not very practical to carry a thermometer over to your friend's house for brunch.
There are other indicators, of course, and you have mentioned the good ones for eggs.
I will add, however, that some indicators can be deceiving. For example, eggs releasing a pool of liquid is actually a sign of over-cooked eggs. The protein matrix is tightening to the point that it's actually expelling water. This is different than runny, uncooked egg.
Similarly, browning isn't necessary for the cooking of an egg (frankly, it's often detrimental). So while browned egg is likely more cooked than not-browned egg, it may also be less done on the inside.
They are clues you can use to identify doneness but none of them are guarantees.
I'd suggest sticking to fried eggs if that's what you enjoy and are more comfortable with.
So to answer your enumerated questions directly:
1) Scrambled eggs cooked to a typical doneness are moist, not-browned, and not expelling excessive liquids on to the plate. If the eggs are not done, they will not be "set" into curds and will be noticeably slimy.
That said, cook them how you like them.
2) Cooking time is dependent on cooking temperature. It's really not a good way to judge doneness. It works better for large cuts of meat or something that will take a lot of cooking time. An individual egg cooking time will vary. Yes, adding additional ingredients (mass) will slow it down.
Overall it will take just a couple of minutes tops. If you start with a hot pan, you can scramble an egg in just a few seconds.
Note: I'm talking about the scrambled eggs you typically see in American diners that look similar to the photos you posted. French style scrambled eggs are creamy in consistency and lack the large curds. Doneness is a little more difficult to judge in that dish.
Best Answer
If you want it fluffy, you'll need air. The easiest way to accomplish this is to crack the eggs in a bowl, whip them (with a whisk or a fork) for a couple of minutes. If you have a homogeneous-ish substance, add them to the onions and potatoes in your pan.