The Apothecary Diaries 04 (Manga) by Natsu Hyuuga

After breaking a "curse" on the imperial heirs, a palace servant with training in herbal medicine is promoted up the ranks to food taster...and right into the thick of palace intrigue in this lushly illustrated historical mystery series! Though Maomao has left the palace behind and returned to her home in the pleasure district, it seems the Inner Court can't do without her! Jinshi comes to the erstwhile food taster with a request involving the attempted poisoning of the Virtuous Consort during the garden banquet and the identity of the mastermind behind it!