In the Jewish religion, what sort of religious rituals are associated with the preparation of food?
Food laws in the Jewish religion are called Kashrut, and determine a set of standards for food content and preparation; acceptable food is "Kosher." A common misconception is that a Jewish Rabbi may "bless" any food item and make it kosher; in reality, the food must be prepared properly and a non-kosher item, such as pork, can never become kosher under any circumstances.
The most important of all kashrut laws is the prohibition against eating meat and milk together. This extends back to Biblical times, and is the foundation of almost all other kashrut laws. To keep this law, most Jewish households have separate dishes for meat and milk products, and some have two sinks or two stoves. This custom is seen in all Kosher food products, which are labeled meat, dairy, or parve (neutral), and is second-nature to practicing Jewish people.
Any plant-based food is automatically kosher from its growth; plants in their raw state need no special preparation to be kosher, although contact with non-kosher food may cause their status to change. The only ritual associated with plants is the blessing said before and after eating, which is a general thanks to God for providing sustenance.
Meat-based foods need more preparation and care to remain in their kosher state. First, all kosher animals must be slaughtered according to exact standards as set out in various works of Jewish law and custom; this process is called shechita, and is usually performed by trained Rabbis, although non-ordained individuals can learn it as well. Judaism prohibits the consumption of any blood, so the meat is salted, sometimes several times, to draw out as much blood as possible. These same procedures are performed for poultry, but not for fish, which are not classified as meat. The prohibition against consuming blood also applies to eggs, which must be checked to avoid blood-spots.
Jewish food preparation is not overly ritualized; some foods, like bread, have customary prayers associated with their preparation because of their highly-spiritual significance. Preparation practices are done more to ensure that the food remains in a kosher state than for spiritual reasons; food that becomes non-kosher is discarded.