"Soup searching" generally means not looking for anything in particular. It just involves setting up a random initial configuration, letting it run until it stabilises ("goes boring") and then takes a census of what's sitting around in the ashes of the burned-out pattern.

Mostly, of course, the census just reports piles and piles of blinkers and blocks and beehives and boats and everything else that you almost always see when you run a random scribble -- but every now and then something turns up that has never ever been seen in the history of Life, and that turns out to be useful and building new mechanisms that weren't possible before:

  https://mathematrec.wordpress.com/2016/07/05/richs-p16/
  https://conwaylife.com/wiki/Rich%27s_p16