Place the herbs in a shallow heatproof baking dish and add oil. Make sure that all the herbs are saturated and covered by the oil.
Place the dish on the middle shelf of a preheated oven set to its lowest setting.
Every 30 minutes, open the oven and stir the herbs in the oil.
This process can take between 30 minutes to approximately 6 hours. (Herbalists differ in their opinions as to how long this will take. As I mention in my blog post, I don't use the Oven method.)
Once the herb and oil mixture becomes fragrant, the process is complete. Remove the baking dish from the oven and transfer it to a heatproof surface. Allow the dish to cool slightly.
Place a mesh strainer over a heatproof vessel and strain and pour the herbs and oil into the mesh strainer.
Allow the oil to drain but DO NOT press or squeeze the herbs. You do not want any particles to transfer through the mesh strainer into the oil.
Once the oil stops dripping, decant the oil into a clean bottle, preferably an amber-colored glass bottle that will protect the essential oils and the olive oil and extend the shelf life.
Allow the oil to cool, and then place a cap on the bottle.
The shelf life for this medicinal herbal oil is approximately 1 year.