Mix the fennel bulbs juice, ascorbic acid, sugar, and salt together.
Dissolve the caster sugar in 100ml of water in a pan then melt the gelatine leaf into it.
Whisk 320ml of fennel juice and albumin powder together then whip in a mixer until tripled in volume.
Slow the mixer and gradually add the warm sugar and gelatine solution until stiff peaks form.
Whisk in the Pernod, spread into a lined dish, sprinkle with fennel pollen, and freeze for 6 hours.
Combine the white and green asparagus spears with olive oil, lemon juice, grated fennel, tarragon, salt, and pepper.
Fry the remaining green asparagus spears in butter until nearly cooked.
Deglaze the pan with lemon juice and beef stock then cook for 2 minutes.
Plate the warm asparagus and the tartare then top with a scoop of the frozen fennel cloud and watercress.