Place mullein flowers and garlic in a clean, dry glass jar. Next, pour in the olive oil – add enough so that the mixture is covered.
Cover the jar with cheesecloth or a paper towel secured by a rubber band.
Place a kitchen towel in the bottom of your slow cooker and place your jar inside. Add enough water to cover about half the jar (making sure not to let the water touch the cheesecloth) and set to the lowest setting for 2-3 hours.
Strain out the oil using cheesecloth and pour the oil in a clean, glass jar. Store in the fridge or the freezer (to preserve freshness) until needed.
Method 2 (Faster)
In Herbal Recipes For Vibrant Health, Rosemary Gladstar suggests a quicker method than the one above: Place mullein and garlic in a double boiler and cover with olive oil. Allow to infuse over low heat for 20-30 minutes, then strain out the garlic/mullein. Store in the fridge or the freezer (to preserve freshness) until needed.
See instructions below this recipe for how to use mullein and garlic oil.