Slightly heat your oil up to about 120F. Just warm enough so that the oil can draw out the flavors of the herb.

Place the tarragon inside the bottle then pour in the warm oil using a funnel to prevent spills.

Let it infuse for a couple of hours. If using neutral oils, the color will slightly change.

Store it in a warm, dark place.

You can experiment with different herbs like rosemary, thyme, dill, etc.