Grab about 15 to 20 beans, then place them on the cutting board. Working quickly, make a uniform pile with them all lined up lengthwise. They don’t all need to be facing the same way! Since you’ll be cutting off both ends, they can be facing different ways.
Line up all the ends against your knife edge. Then grab them in one hand, and cut off the ends with a knife.
Quickly flip the beans the other way, and then push them towards your knife blade so that the other ends line up (see the photo above). Then grab the pile and slice off the other ends.
If the recipe calls for bite sized pieces, slice the beans further to make bite-sized pieces.