Just in case you wanted to know, the Section 422.16 (B) (3) of the California Electric Code for 2013 contains the following:
(3) Wall-Mounted Ovens and Counter-Mounted Cooking Units. Wall-mounted ovens and counter- mounted cooking units complete with provisions for mounting and for making electrical connections shall be permitted to be permanently connected or, only for ease in servicing or for installation, cord-and-plug-connected.
A separable connector or a plug and receptacle combination in the supply line to an oven or cooking unit shall be approved for the temperature of the space in which it is located.
So, if you wanted to replace your oven’s direct wiring with a plug (in case you were experimenting with something that required 240 V power), you’re good to go (assuming you do it right).