The LSST project is developing a set of sophisticated simulation tools that allow the user to produce realistic LSST images. These tools include CatSim, simulating the LSST sky, and PhoSimwhich draws phtons from the simulated sky through the atmosphere, LSST telescope and CCD electronics. The simulations recipe book is a user-generated set of worked examples for these tools in the form of usable code. The recipes are python scripts that generate (and even analyse) simulations for a specific task. The utensils are shorter 'helper' scripts which perform specific, commonly-used functions. In a longer time-frame, these recipes and utensils will be assembled into a library of functions that users can put together to make a science analysis.
This is a useful complement to the documentation provided by the various simulation projects themselves. Instead of describing what the simulations do, they will demonstrate how the simulation framework can be used to do science. These recipes will therefore not only instruct scientists in how to adapt and use the simulation tools, but also showcase the many ways the tools can be used. They will hopefully prompt new ideas for using the simulations in DESC science analysis.
You can find the recipe book on the DESC github page: http://darkenergysciencecollaboration.github.io/ImageSimulationRecipes/.