Place all the ingredients into a jar and secure the lid.
Shake well until combined.
Notes
You can use fresh oregano instead of dried oregano. Fresh oregano has a vibrant, herbaceous flavor that will complement your Greek salad dressing. Just substitute the dried oregano with a tablespoon of finely chopped fresh oregano leaves. Keep adding more until you're happy with the taste.
If you don't have red wine vinegar on hand, another vinegar with a similar tangy flavor profile (think apple cider vinegar or white wine vinegar) should suffice. The taste of the dressing will change, obviously, so sample as you add the substitute.