Meanwhile, make the pickling liquid. Add the vinegar, water, sugar, salt, peppercorns, mustard seeds and red pepper flakes into a small saucepan set over medium heat.
Place the beet wedges, garlic, and dill into a quart sized canning jar, leaving at least 1/2" to the top of the jar. Pour the pickling liquid over the beets into the jar, leaving 1/2" headspace.