Slicing is the cutting of food into thin, relatively broad slices. Slices may be used as they are or processed further to produce other speciality cuts such as chiffonade, rondelles, diagonals, oblique or roll cuts, and lozenges. Slicing may be accomplished by hand or machine. Mechanized slicers include rotary slicers and food processors with a slicing attachment. A mandoline greatly increases both the speed and uniformity of slices produced and are available for both professional and home use.
The tip of the knife rests on the cutting board while the food item is held with the other hand. The knife is rocked up and down. On the downward movement, the blade moves down and forward to slice through the item, keeping the tip on the cutting board. If the item is too large to rest the tip on the work surface, the same motion is used but the tip points toward the cutting board while one pushes the knife down and forward through the food in one movement. Do not saw backwards and forwards.
Gripping the item with one's fingers curled under as described, use the wrist as a fulcrum and the second joint of one's index finger as a guide. With the heel of the knife on the cutting board, the tip is lifted and one slices by drawing the knife slightly back toward you and down through the item, using the knuckle of the index finger to adjust the thickness of each cut. The motion of the knife should be almost entirely from the wrist, not from the elbow.
Knives should always be kept sharp and stored separately from other utensils. Cuts occur more frequently with dull knives because they have a tendency to slip off the food being cut. Never leave knives in a sink full of soapy water. Never try to catch a falling knife. Never try to clean the circular blade of a mechanical slicer while the machine is still assembled. Always ensure that mechanical slicers and other electrical cutting equipment are disconnected from the power supply before disassembling them for cleaning. When using a mandoline, use the food holder which is supplied with it. If it didn't have one when you bought it, it is quite likely being illegally sold in your jurisdiction which probably requires that they be sold with a holder included.
When slicing food by hand, always grip the handle of the knife firmly. A loose grip can lead to accidents. The food item is held firmly with the other hand, the fingers curled under, so that the side of the blade is against the knuckles. The curling under of the hand holding the food is extremely important and a safety requirement that must never be disregarded even when the knife is nowhere near one's fingers, so as to make it a habit that becomes automatic. Many accidents, and indeed the loss of digits, could have been avoided if this technique were always followed. Regrettably, even professionals sometimes disregard their own rules. Resist the temptation to do so.