Cook the blackcurrants

• Put the blackcurrants, sugar and water in a saucepan.
• Bring to a simmer and cook until the fruit has collapsed and released its juice.

Strain the purée

• Pass the mixture through a fine sieve, pressing well to extract as much juice as possible.
• Discard the seeds and skins.

Set with gelatin

• Soak the gelatin sheets in cold water until soft, then squeeze out the excess water.
• Warm a little of the blackcurrant juice and dissolve the drained gelatin in it.
• Stir the dissolved gelatin and the lemon juice back into the rest of the juice.

Chill the base

• Let the blackcurrant base cool completely in the fridge.

Fill the siphon

• Blend the cold base with the cold cream until smooth.
• Pour the mixture through a sieve into the siphon.
• Close the siphon and charge it with one cream charger, shaking well.
• Keep refrigerated until serving.

Serve

• Shake the siphon and spray the espuma into chilled glasses or onto the dessert.
• Serve immediately.