Add all ingredients to a glass jar and shake to combine.
Store unused vinaigrette in the refrigerator. Pure olive oil will turn hard in the fridge, so set it out a few minutes before using. Shake it immediately before pouring onto a salad.
Notes
I've indicated that marjoram is optional. It's difficult to find, and I don't always have it on hand. If you have some, throw it in. If not, your dressing will be fine without it.