My omelettes are whisked with a fork. To get them properly fluffy, make sure the oil is hot enough, cold oil is a much bigger problem for “flat” omelettes than “not having mixed it enough.”
One of my brothers likes his omelettes with the general solidity of a brick, so we know how to get them both ways
I use a whisk. And oil is all wrong, people! Use butter. But if you really want a fluffy omelet, it’s not oil/butter or whisk/blender/fork that makes the difference. What really matters is that you add a bit of water - not milk. That will make your omelet super fluffy.
Quasi, if I want my omelettes to be super-fluffy, I separate the eggs and fluff up the whites, first. I only use a fork though. After fluffing them up, I put the yolks back and just fold them in, three or four strokes. Makes nice and puffy omelettes!
A great part of omelet fluffiness is proper cooking technique.
Cook over low heat, and whisk/stir while it’s in the pan, right up until the point its solidifying. It’s sort of like scrambled eggs, only you just want to slightly stir as opposed to creating huge curds. Tilt the pan to fill in any holes you might create. When it’s almost done, stop stirring.
I use a whisk and add a bit of water. Then cook slowly with butter, not agitating too much, just pulling in the sides as it cooks and tilting the pan so the uncooked egg fills the gap. My key, though, is to cook slowly, cook too fast and you squeeze all the moisture out of the egg and it gets tough.
I break the eggs into the frying pan, add a little milk, cook on low heat for a bit, then add the fillings (usually ham and cheese) and finish cooking.
Serve with toast and tomato ketchup.
As this is the SDMB, I shall study your whisking suggestions with interest.
I bet a blender would get them super fluffy, but who wants to clean a blender up? I use a whisk if I remember, a fork more often, melt butter in the pan and eat at my desk all the time.
The most important tip I’ve read is to make sure the eggs are not cold. The French don’t refrigerate their eggs so it’s assumed they’ll be a room temperature. Cold egg behaves differently than warm or room temperature egg. Put them in a glass of warm water to get them warmed up ahead of time.