This is done by placing the saucepan with only half of it on the heat source so that the liquid simmers only on one side. This pushes the fat to the opposite side and makes it easier to lift off with the ladle. The fat can then be skimmed off by holding the ladle so that the top of its bowl is almost level with the liquid and then tilting it slightly and in a circular motion toward the edge of the saucepan where the fat accumulates.
To accomplish this, place the saucepan on the heat source with only half of it exposed. This causes the liquid to simmer on one side, pushing the fat to the opposite side and making it easier to scoop out with a ladle. Then, tilt the ladle slightly in a circular motion toward the edge of the saucepan, where the excess fat collects.