Boil eggs for 10 minutes; cool in ice water and peel.
In a saucepan, combine vinegar, water, sugar, salt, peppercorns, mustard seeds, red pepper flakes, garlic, onion, dill, and bay leaf; boil and simmer 5 minutes.
Taste and adjust the brine with sugar or salt.
Cool brine slightly (5–10 minutes).
Place eggs in a 1-quart jar; pour brine over to submerge.
Seal and refrigerate for 3–7 days.
Serve in a white ceramic bowl or jar with a cheese platter.