Clean fennel and cut lengthwise into narrow strips. Chop fennel greens very finely and set aside. Halve chicory lengthwise, remove bitter stalks, cut into strips about 1 cm wide and mix with fennel strips. Halve the apple, remove the core and cut into narrow wedges. Sprinkle these with lemon juice.
Remove peel from first grapefruit and fillet. Squeeze out the rest and collect the juice. Squeeze second grapefruit, add juice to that of the first and stir in whipped cream. Sweeten sauce with Frutilose and season with cayenne pepper and sea salt.
Mix the sauce with the prepared ingredients and sprinkle with fennel greens and almond flakes.