Whisk (or shake) together all ingredients until completely combined.
Notes
Finely mince, press, or grate your garlic. You don't want any big chunks of garlic floating around in your dressing.
Use the highest quality balsamic vinegar and extra virgin olive oil that you can find. They will make the difference between a thin, flavorless, runny salad dressing and a thick, robust, rich balsamic vinaigrette!
Stream in the olive oil slowly while whisking continually. This helps emulsify the dressing, bringing all of the ingredients together. Alternatively, you can shake the ingredients together in a mason jar.
Taste the vinaigrette by dipping a piece of lettuce or other salad greens into the dressing. This will give you a better sense for how the vinaigrette will actually taste on your salad.
Adjust the amount of salt and pepper to suit your personal taste preferences. I also like to season the lettuce greens with salt and pepper.
If using delicate lettuce or baby greens, wait to dress the salad until you're ready to serve. If you're using sturdier greens, like kale, you can toss the salad in advance and let it sit in the fridge for a few hours.