Sous-Vide Rhubarb & Rose Water Kefir Tonic with Spring Pea and Mint

Equipment

• Sous Vide
• Vacuum Sealer
• Kitchen Scale

• ▸400 g fresh rhubarb stalks, cut into 2 cm pieces
• ▸120 g cane sugar
• ▸2 tbsp rose water, food-grade
• ▸1 tsp cardamom pods, lightly crushed
• ▸1/2 tsp dried culinary-grade rose petals, plus extra to garnish
• ▸200 g fresh spring peas, shelled (about 1.5 cups)
• ▸15 g fresh mint leaves, plus sprigs to garnish
• ▸500 ml whole milk kefir, plain, live-culture
• ▸200 ml cold sparkling water
• ▸1 tsp raw honey, to taste
• ▸1 pinch fine sea salt
• ▸1/2 tsp sumac powder, for dusting
• ▸ice cubes, to serve

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   1. SET YOUR SOUS-VIDE BATH: Fill a large container or pot and set your immersion circulator to 63°C (145°F). This precise low temperature will extract rhubarb's oxalic brightness and tannins without scorching the delicate rose and cardamom aromatics.

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   2. MAKE THE RHUBARB-ROSE CORDIAL POUCH: Combine the rhubarb pieces, cane sugar, rose water, crushed cardamom pods, and dried rose petals in a zip-lock or vacuum-seal bag. Remove as much air as possible using the water-displacement method or a vacuum sealer. Seal tightly.

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   3. SOUS-VIDE THE CORDIAL: Submerge the sealed bag in the 63°C bath and cook for 2 hours. The rhubarb will break down completely, releasing a vivid crimson syrup infused with cardamom and rose. After 2 hours, remove the bag and let it cool to room temperature (about 20 minutes), then refrigerate until cold.

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   4. STRAIN THE CORDIAL: Strain the contents of the bag through a fine-mesh sieve lined with cheesecloth, pressing gently on the solids. You should have approximately 250–300 ml of jewel-red cordial. Discard the solids. Refrigerate the cordial.

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   5. JUICE THE SPRING PEAS: Blanch the shelled peas in boiling salted water for 60 seconds, then shock in an ice bath and drain. Blend the peas with 50 ml cold water until completely smooth. Strain through a fine-mesh sieve, pressing hard to extract all juice. You need approximately 80 ml of bright green pea juice. Refrigerate immediately to preserve the color.

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   6. MAKE THE MINT INFUSION: Gently bruise the fresh mint leaves with the flat of a knife. Combine with the pea juice and let steep in the refrigerator for 30 minutes. Strain out the mint leaves and discard.

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   7. BLEND THE KEFIR BASE: In a large jug, whisk together the cold plain kefir, the strained rhubarb-rose cordial, and the mint-infused pea juice. Add the pinch of sea salt and the raw honey. Taste and adjust sweetness — it should be pleasantly tart and floral with a green, grassy undertone.

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   8. FERMENT (OPTIONAL BUT ENCOURAGED): For a deeper, more complex tonic, pour the blended mixture into a clean glass bottle or jar, seal loosely (to allow CO2 to escape), and leave at room temperature for 2–4 hours. The live kefir cultures will begin a secondary fermentation, adding natural effervescence and deeper tang. Refrigerate immediately after to halt fermentation. Skip this step if you prefer a milder drink.

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   9. ASSEMBLE THE DRINKS: Fill four tall glasses with ice. Pour the kefir tonic mixture evenly between glasses, filling about three-quarters full. Top each glass with a splash of cold sparkling water for extra effervescence.

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    10. GARNISH AND SERVE: Dust each glass lightly with sumac powder (its fruity tartness amplifies the rhubarb). Add a fresh mint sprig and a pinch of dried rose petals on top. Serve immediately with a long spoon for stirring, as the pea juice will settle slightly — that green swirl rising through the pink is half the point.

Nutrition (estimated per serving)

Calories

178

Fat

3g

Carbs

34g

Protein

6g

Fiber

3g

Sodium

112mg

Variations

• ◆Dairy-free: swap whole milk kefir for coconut milk kefir or water kefir. The drink turns lighter and more tropical, though you'll lose some creamy tang, so add an extra teaspoon of sumac to compensate for the lost acidity.
• ◆Spiked tonic: stir in 30 ml of good arak or dry vermouth per serving before topping with sparkling water. The anise notes of arak echo the cardamom and produce an unexpectedly sophisticated cocktail that still has genuine probiotic credentials.
• ◆Granita: pour the finished blended tonic (before adding sparkling water) into a shallow freezer-safe dish and freeze, scraping with a fork every 45 minutes for 3 hours. Serve in chilled glasses topped with rose petals as a palate cleanser between courses.

Storage & Make-Ahead

The rhubarb-rose cordial keeps well in a sealed jar in the fridge for up to 5 days, and it actually deepens in flavor after 24 hours as the cardamom settles in. The blended pea-mint base is best made the day you're serving, since the peas oxidize and lose their bright green color within a few hours, but you can shell and blanch the peas a day ahead and refrigerate them. Assemble the full tonic, including the kefir and sparkling water, only when you're ready to drink it, as the carbonation goes flat and the kefir separates if it sits more than 30 minutes. The cordial freezes well in ice cube trays for up to 3 months, which makes it easy to pull out a portion for a single glass without thawing a whole batch.