Combine all ingredients in a jar with a lid. Seal tightly and shake to combine. Of course you can also use a bowl and whisk, but I think using a jar is a lot easier.
Store in the refrigerator for up to two weeks.
Notes
Important note: If you are using regular balsamic vinegar you may want to cut the quantity back to 1/4 cup. Aged balsamic vinegar is much sweeter with a smoother taste, so that's why I use equal parts of oil and vinegar. It's a little bit of a splurge but I think it is worth it. Plus when using a good quality aged balsamic vinegar, the taste will not overwhelm the salad.