Preserving Fresh Herbs in Oil
Submerging fresh, hardy herbs in oil creates a base that traps aromatic oils and protects the leaves from oxidation. By packing herbs tightly into a sterilized jar and covering them completely with neutral oil, you create a shelf-stable way to store intense flavor for several months.
Moisture is the enemy
The herbs must be bone-dry after washing, or the water trapped on the leaves will cause the oil to turn rancid or encourage unwanted growth. Use hardier herbs like rosemary, thyme, or oregano for the best results.
- small mason jar
- paper towels
- funnel
- sterile tongs
What goes in.
- 2 cupsfresh hardy herbs (thyme, rosemary, oregano)
- 1-2 cupsneutral oil (grapeseed or mild olive oil)
Submersion Strategy
The oil acts as a barrier against oxygen. If any leaf tips poke above the surface, they will brown and compromise the entire jar.
The method.
Dry the herbs
Wash the herbs thoroughly and lay them flat on a clean kitchen towel. Pat them dry and let them air dry for at least an hour until no beads of water remain.
Pack the jar
Strip the tougher woody stems if necessary. Pack the herbs into a clean, dry jar until it is about three-quarters full. Do not crush them, but ensure they are densely nested.
Add the oil
Pour the oil over the herbs until they are fully submerged by at least an inch. Tap the jar against the counter to release any trapped air bubbles.
Seal and store
Place a small piece of parchment paper over the opening before tightening the lid to ensure an airtight fit. Keep the jar in a cool, dark cupboard.
When it doesn't go to plan.
Use a small jar so you can finish the contents within a few weeks once opened.
Label the jar with the date to keep track of how long it has been stored.
If the oil begins to look cloudy or smells off, discard it immediately.
The ones that keep coming up.
Can I use soft herbs like basil or cilantro?
Soft herbs have a high water content and thin cell walls, which makes them prone to spoiling quickly in oil. It is safer to stick to woody, low-moisture herbs.
Do I need to heat the oil?
No. Cold-infusion preserves the bright, raw character of the herb better than heating, which can cook the leaves.