How To Make An Oil With FRESH Herbs
Chop your herb into small pieces using clean scissors or pruners. Place herb bits slightly packed in a mason jar (what size mason jar you use will depend upon how much herb you have). Pour oil into the jar and, using a non-metallic object (like a bamboo skewer or the wooden handle of a spoon), stir the oil to ensure all the herb is coated with the oil. Add more oil to the top of the jar, place on lid and screw cap, and let sit in the pantry for 6 weeks.
You can line the lid with a piece of parchment paper or cling wrap, if you like, to prevent the oil from touching the metal. Strain out the plant material using a fine sieve (you can place an unbleached coffee filter into the sieve first), or use a nut milk bag. Pour the oil into sterilized amber jars and label. Shelf life kept in a cool, dry place is 1 year.
Often, infused oils are used for external application, for example, as a massage oil or a body or face oil. These infused oils are also often turned into salves (another word for balms), where melted beeswax and candelilla wax are used to turn the oil into a solid product. You can check the basic how-to make a salve recipe HERE or discover salves for face and body HERE.
You can also make infused oils for internal use as well. A great example is infusing fresh Italian herbs like Basil, Rosemary, and Thyme into olive oil, and then using this oil to add that special je ne sais quoi in your salad dressings and vinaigrette recipes (you can find that recipe HERE :)).
NB. The parts of the plant that are used in infused in oils are the flowers, stems and leaves. Often, organic olive oil is used (cold pressed, virgin or extra virgin). However, there are many other oils that can be used depending upon what the infused oil will be used for. A few other commonly used oils include grapeseed oil, sunflower oil and jojoba oil.
NB. Since oils go rancid, it is common to add preservatives to increase the shelf life of the oil. This is especially true if the oil will be used for cosmetic purposes. Common natural preservatives that are added include Vitamin E oil and essential oils (EOs) with antibacterial, antiseptic and perhaps anti-fungal properties, such as Rosemary, Sage, Tea Tree and Eucalyptus EOs. This is not an exhaustive list and there is a lot of room for play here :)
How To Make An Infused Oil With DRIED Herbs
Place herbs in a crock pot and cover with olive oil. Stir to coat herbs with the oil using a non-metallic object. Add in 1-2 inches more olive oil to cover. Put on Low to gently warm the herbs for 1-2 hours. You want to linger around, because you DO NOT want the oil to cook (it will smell like cooked oil and won't be pleasant to use). Turn off heat and let cool.
Strain out the herbs using a nut milk bag or fine mesh sieve lined with a coffee filter. You can now pour into sterilized amber jars or use this oil to make a salve. As with infused oils using fresh herbs, you can add in Vitamin E and EOs to increase the shelf life of your oil and make it smell nice :)
NB. Do note that other oils can be used besides olive oil, as with infusions using fresh herbs. If you're wondering how much herb to use, you can use as little or as much as you want, depending upon how much oil you need. It might also be good to know that the shelf life of infused herb oils is about 1 year, so if you think you may need more oil at a future date, then you might want to make a good amount.
The key points in making a dried herbal oil infusion is that you cover the herbs with enough oil. And secondly, that while you can gently warm the oil using a double boiler or glass/ ceramic pot, be sure to keep the temperature on low to avoid cooking the oil. The last you want is to smell like fried oil on your skin ;)