Combine apple cider vinegar, water, sugar, kosher salt, peppercorns and bay leaf in a small saucepan and bring to a gentle simmer to dissolve sugar and salt. Remove from heat and let cool to warm.

Pack jars

Place peeled pearl onions into a clean jar. Pour the warm brine over the onions, making sure they are fully submerged. Seal and refrigerate at least 24 hours; flavor improves over 48 hours.

Smoke the onions (short method)

To add a pronounced smoke character, place drained pickled onions on a rack in a large metal bowl. Heat a small pinch of wood chips in a metal smoking box or foil pouch until smoldering and place under the rack; cover tightly with a lid or foil for 5–8 minutes to capture smoke. Cool and refrigerate. Alternatively, cold-smoke onions for 10–20 minutes if you have a cold smoker.

Cocktail Assembly

Chill glass

Place a coupe or martini glass in the freezer or fill with ice water while you prepare the cocktail so the glass is well chilled.

Measure and combine

In a mixing glass, pour 2 oz Tanqueray gin, 0.75 oz well-chilled dry vermouth, 0.25 oz smoked pickled onion brine, and 1 dash orange bitters.

Stir with ice

Fill the mixing glass with plenty of ice. Stir gently but thoroughly for 30–45 seconds (about 20–30 strokes) until the mixture is well chilled and slightly diluted.

Prepare smoke chamber (optional, for presentation)

If presenting with smoke: place the smoked wood chip on a heat-safe surface and briefly ignite until it smolders (or use a smoking gun). Set the chilled glass upside down over a small bowl or use a cloche to capture smoke. If using a smoking gun, fill the glass with smoke and set aside until ready to pour.

Strain

Discard ice/water from the chilled glass. Double-strain the mixture from the mixing glass into the chilled coupe or martini glass using a julep or fine strainer to remove any small ice shards.

Garnish and finish

Skewer a smoked pickled onion on a cocktail pick and rest it in the glass. If you prepared a smoke chamber, release the trapped smoke over the cocktail just before serving (lift cloche or tilt glass to expose). Optionally express a lemon twist over the drink and discard or drop into the glass.