Rinse the curry leaves under running water, then towel them dry.
Trim away the woody end of the compound curry leaf's stem. While the smaller, more tender and flexible portions of the stem may remain in place, you can trim them off if you would like.
Add 2 tbsp. vegetable oil to the pan.
Turn a stove burner to its lowest heat setting and set the pan on the burner.
Add the curry leaves to the pan.
Stir the curry leaves slowly with your wooden spoon. Stir frequently, almost continually. Never leave the pan unattended. The curry leaves are dry enough to powder when they crumble readily when pressed gently with the wooden spoon.
Remove the curry leaves from the pan and place them on a plate. Leave them there until they return to room temperature.
Grind the curry leaves in a food processor at the highest speed setting (following the manufacturer's instruction) or by hand with a mortar and pestle. Stop grinding when the curry leaves are the consistency of a loose powder.
Store the curry leaf powder in an air-tight container in a cool, dark place until you are ready to use it.