Making infused oils is easy with oily, woody herbs such as rosemary, tarragon and sage. You can also add strips of lemon zest, peppercorns, bay leaves and other woody herbs to your bottled oils to make them look pretty.
Don’t try to infuse oil with soft-leaf herbs such as basil or oregano as they won't keep in the oil safely – they are too moisture dense and will go mouldy.
Over a low heat, warm 250ml extra virgin olive oil in a wide, deep saucepan. Add 4 peeled, whole garlic cloves and a few washed and dried rosemary sprigs. Warm gently for five minutes, then use a slotted spoon to transfer the garlic and rosemary into a sterilised, dry bottle or jar. Add peppercorns and mustard seeds if desired. Pour over the oil, making sure that it reaches the top of the bottle and completely covers the rosemary. Seal the bottle.