Rhubarb Recipe

Prepare rhubarb base

Wash and trim rhubarb stalks, discard any leafy tops. Chop stalks into 1/2-inch pieces until you have about 4 cups. Place chopped rhubarb in a large nonreactive pot.

Make simple rhubarb syrup

Add 1 cup granulated sugar and 250 ml water to the pot with rhubarb. Bring to a gentle simmer over medium heat, stirring to dissolve sugar. Simmer 8–10 minutes, stirring occasionally, until rhubarb is softened and syrup is fragrant. Remove from heat and let cool to room temperature (about 30–45 minutes).

Add kōsho aromatics

When the rhubarb syrup has cooled to room temperature, stir in the chopped seeded chili, sliced ginger and 2 tsp kosho-style paste (or the lime zest + sea salt substitute). Taste to confirm a balance of bright citrus, salt and mild heat — it should be assertive but not overpowering.

Pitch yeast and ferment

Pour the cooled rhubarb-sugar mixture into a sanitized 1–2 L wide-mouth glass jar or demijohn, leaving 10–15% headspace. Sprinkle 1 tsp champagne or wine yeast on top and gently stir to distribute. Fit an airlock or loosely cover with a clean cloth secured with a rubber band to allow CO2 to escape. Store in a cool, dark place (18–22°C / 65–72°F) for 3–7 days, checking daily. You should see light bubbling and a change in aroma. Ferment until activity slows and the flavor has developed (typically 3–5 days for a short ferment for liqueur style).

Strain and fortify

When fermentation slows, strain the mixture through a fine mesh sieve lined with cheesecloth into a sanitized bowl or container, pressing to extract liquid. Discard solids. Measure the strained rhubarb liquid volume and transfer to a large jar. Add 500 ml Old Rye whiskey to the strained rhubarb liquid as the fortifying spirit (this yields a strongly flavored liqueur — for a milder result add less whiskey). Stir to combine, then taste and adjust salt or lime if needed. Transfer to sterilized bottles, seal, and let rest for at least 1 week to marry flavors. Store refrigerated or in a cool dark place. The finished liqueur will keep for several months; chill before using in cocktails.

Notes on adjustment

If the liqueur is too sharp, add 1–2 tablespoons of simple syrup (1:1 sugar:water) to soften. If heat is too strong, let the liqueur rest longer or dilute slightly with more whiskey or water when mixing cocktails.

Prepare glassware: chill six highball or Collins glasses in the freezer briefly or fill with ice water while you assemble the first cocktail.

Measure and pour rye: For each cocktail, add 90 ml Old Hunter Rye into a mixing glass or shaker filled with ice.

Add liqueur: Add 30 ml fermented rhubarb kōsho liqueur to the mixing glass with the rye.

Stir briefly: Stir the rye and liqueur together with ice 10–15 seconds to chill and gently dilute. This blends the fortified liqueur and whiskey without bruising aromatics.

Build in glass: Fill the chilled highball glass with fresh ice. Strain the stirred whiskey + liqueur mixture over the ice.

Top with mandarin soda: Gently top each glass with 120 ml chilled mandarin soda (or mandarin-flavored soda water) to add effervescence and citrus lift. Stir once gently to combine.

Garnish and serve: Express the oils of a mandarin peel over the drink or drop in a mandarin segment. Optionally, add a thin rhubarb ribbon for visual appeal. Serve immediately.

Serving note: This recipe yields 6 cocktails using the listed per-serving amounts. Adjust proportions proportionally for more or fewer servings.