Step 1: Wash and boil
The pods are kind of hard, and you want to get the seeds out, so unless you are fanatical about keeping your carob raw, boil them for about 20 minutes.
Step 2: Split pods
Step 3: Deseed
Step 4: Dehydrate
You can dry the ground pods in the oven at low temp or in a dehydrator overnight. The dryer the stuff, the smoother your powder. Don't rush this step, it is key!