Place the chopping board on a damp cloth. Remove any loose papery skin from the onion to stop your knife from slipping when making the first cut.
Cut off the root end of the onion.
Stand the onion on the cut root end and slice the onion in half downwards from stalk to root end.
Take one onion half and carefully peel away the papery outside layers.
Place onion cut side down on chopping board and make several cuts downwards from just short of the stalk end to the root end. The uncut stalk end will help keep the onion together. Adjust these cuts to the fineness of the chop you require.
Now slice across these cuts, from the root end back to the stalk end. Hold the onion whilst you do this with your fingers curled under and using your second finger knuckle to guide the blade. Again, adjust the slicing to the fineness of the chop you will require.
Discard the last part of the stalk end and repeat for the other onion half.
notes
Always put a damp cloth under the chopping board to prevent it from slipping.