Whenever I’m in San Francisco for work, I bring back a loaf or two of San Francisco Sourdough.
I get it from Boudin Bakery, which has used the same sourdough starter since 1849; likely making it one of the longest still-in-use starters in the world.
The best part is they have a shop at the airport where you can buy take-and-bake loaves. To finish them off they simply require 10-mins in the oven at home.
There’s something special, albeit irrational, about taking two loaves of sourdough across an ocean to have them baked, warm, and fresh in London. It’s a unique experience that always serves as a nice bookend to a trip.