- Crack an egg into a small bowl. Find a clean, empty plastic bottle with a slightly wide mouth.
- Squeeze the bottle, then kiss the egg yolk with the opening. (Touch it lightly so the yolk doesn’t break.)
- Let the air out of the bottle so it sucks up the yolk. Quickly tilt the bottle back (so the yolk doesn’t fall out).
- Squirt the yolk into a separate bowl.
If you want to understand how this works – here’s the details from Steve Spangler Science:
When you squeeze the bottle, you are decreasing the air inside. If you squeeze the bottle while the mouth is facing towards you, you’ll feel air rush out. Releasing the squeeze on the bottle allows air to rush back into the bottle. If you cover the mouth of the bottle with the egg yolk prior to releasing the squeeze, the available volume inside the bottle is filled by the egg yolk.
Extra tip for separating eggs:
Although many recipes require eggs to be at room temperature, it is easiest to separate eggs that are cold. Eggs that are at room temperature can be separated, but this requires greater caution to avoid breaking the yolk. Wikipedia