Break Caulilini into florets.
In a large saucepan, combine apple cider vinegar, water and sea salt. Bring to a boil.
Place the lemon slices in the bottom of a quart jar and top with garlic clove slices, peppercorns, mustard seeds and bay leaves. Set aside.
When brine is boiling, add Caulilini to the pot. Stir until the brine returns to a boil and remove from heat.
Using tongs, pack Caulilini into the prepared jar and top with brine.
Place 2-3 slices of lemon strips on top of the Caulilini and put a lid on the jar.
Let pickled Caulilini sit out on counter until cool. Once they’ve reached room temperature, refrigerate jar.
Pickled Caulilini is ready to eat within 12 hours, though they will continue to deepen in flavor the longer the rest.