Circuit to avoid reasonable overcurrent and ESD protection for UART

Background and goal: I have a raspberry pi that communicates via the UART (gpio-pins) at 115200 baud with another microcontroller (that I do not have control over and can't modify). That controller gets fed power from an USB-port which allows for 5V and only small currents. So from the other device I have 3.3V based UART rx/tx, GND and 5V. My goal is to put something inbetween these two parts and make them galvanic separated (right words?) so that when a lightning strikes and burns my raspberry, nothing happens to the other microcontroller. I understand that a direct hit with a lightning strike will probably blow the house away, but what I'm after is something reasonably good. I have these things at home that I put between my power-socket and my device that can handle lots of voltage and spikes. To keep things yet more reasonably, I'd like the components to be no more expensive than I can buy them for max $10-15. This will keep expensive fiber-optivs-solutions at bay I think... Requirements: * You should have Experience and/or know Best practices in this field in addition to just reading up on the rms-values etc. from datasheets. Deliverables: * A simple schematic (napkin is ok, as long as I can understand it) * BOM for me to build it, Preferrably from Farnell if possible (All through-hole please) Please use direct messages or ask in the public board and I'll try to clarify req.