Combine vinegar, 3/4 cups water, sugar, and salt in a small saucepan, place over medium heat, and simmer for several minutes to dissolve the sugar and salt. Cool to room temperature.

In a small bowl, combine garlic, shallot, peppercorns, mustard seeds, and red pepper flakes. Add half of this mixture to a quart Mason jar. Add cinnamon sticks, dill, and bay leaf. Place 3 eggs into the jar and top with remaining spice mix. Place the last 3 eggs into the jar and pour the cooled vinegar mixture into the jar to cover them, but leave at least 1/2 inch of headroom in the jar. Cover and place the jar in the refrigerator for 5–7 days before eating the eggs.