Unquote #20 answer

The quote

The sea was angry that day, my friends - like an old man trying to send back soup in a deli.

The puzzle as it was set

DQY KYB MBK BRLVN DQBD ABN, WN SVXYRAK - FXZY BR IFA WBR DVNXRL DI KYRA GBUZ KICE XR B AYFX.

The key

Each code letter stood for one real letter (code letter, then the real letter it hid):

B → AG → BU → CA → DY → ES → FL → GQ → HX → IZ → KF → LW → MR → NI → OE → PV → RK → SD → TC → UM → WN → Y

The most frequent code letter was B (9 times), which stood for A. Short words, apostrophes and repeated letters are the usual way in: a one-letter word is almost always A or I, and THE is the commonest three-letter word in English.