Cut In, to Cut In
To work a solid fat, such as shortening, butter, or margarine, into dry ingredients i.e. flour. This is usually done with a pastry blender, two knives in a crisscross fashion, your fingertips, or a food processor. Smaller chilled pieces of fat work best as even the heat from your fingertips can cause the fat to melt, and ruin your desired end result.