How do you make a cup of tea for Duke in Professor Layton and Pandora's Box?

Duke, (Boy at the gate) Likes Tea No 6.

6 Bitter Fruit Contains:

Brisk Berry Sweet - Citriona Seed Sour-Tonic Flower Bitter.

Brisk Berry Sweet = Revitalising - Citriona Seed =Good for the Skin -

Tonic Flower Bitter = Boosts Immunity