First get some calf liver from your butcher or supermarket. Clean the membrane off the surface of the liver, remove the vein and give it a wash.
Slice the liver across the width into fine strips (the finer the better) and place onto a non-stick tray.
Dry out in a coolish the oven (approx 100degrees C or 200 degrees F) until hard and brittle but not burned. Depending on how thick you cut the liver you may need to turn a couple of times.
Once done remove from oven and allow to cool.
You can either keep as large pieces for treats or chop into smaller ‘positive reinforcement’ sized pieces for training.
They keep in an air tight container in the freezer for ages.
Love your Doberman.