Tea
Tea; dried leaves of a particular plant submersed in hot water and allowed to brew.
The Doctor drinks a lot of it.
Brigadier Lethbridge-Stewart has occasionally used tea to break up the conversation, offering it to Zoe when she became worried of the Doctor's safety when he was pursuing Tobias Vaughn. (DW: The Invasion)
During his time with UNIT the Doctor drank a lot of tea. Only the tea lady and the Brigadier could come into his lab. (DW: Terror of the Autons) He also made a habit of stirring his tea with anything available such as a silicon rod. (DW: The Three Doctors)
Sarah Jane Smith has often muttered / mentioned that she could "murder a cup of tea". (DW: The Time Warrior)
Whilst in Victorian London the Doctor and Professor Litefoot attempted to educate Leela on the etiquette of Tea. (DW: The Talons of Weng-Chiang)
The the Doctor has once described tea to his companion Turlough as "a noxious infusion of oriental leaves containing a high percentage of toxic acid." (DW: The Awakening)
Captain Cook offers many people tea and even when captured within the Greatest Show in the Galaxy is still able to drink tea. (DW: The Greatest Show in the Galaxy)
During the Shoreditch Incident the Doctor goes to a cafe within central London and has a mug of tea, and discusses many things on his mind around the nature of evil and destiny. (DW: Remembrance of the Daleks)
The Doctor whilst in his seventh incarnation was particularly fond of Lapsang Souchong tea, a style which Provost-Major Beltemst also appeared to enjoy. (NA: Original Sin)
When the TARDIS is destroyed the Doctor and Fitz sit around talking about all the tea they used to love drinking which is now gone. (EDA: The Shadows of Avalon)
Whilst in Cardiff the Doctor and Rose take tea with Charles Dickens at Mr Sneed's house, served by Gweneth. (DW: The Unquiet Dead)
Tea was also able to assist the Doctor in his post-tenth regeneration recovery. (DW: The Christmas Invasion)