Sorry, this should have been on the CF.

From Sfgate.com:

Using cazuelas: Libby Creed, of the Spanish Table in Berkeley, gives these instructions:

Before using it the first time, soak the cazuela in cold or tepid water for at least 6 hours. It need not be soaked again; once is enough. The cazuela can be used on the stove-top, in the oven, on a grill, in a clay or brick oven, and in the microwave. Cazuelas are dishwasher-safe, but position them carefully to avoid chipping the glaze. Until the cazuela has been broken in --

that is, used many times -- keep stovetop temperatures at low or medium, and oven temperatures at 400 degrees or less. After the cazuela has been broken in, it can be used to fry fish, bring a stew to a full boil, and brown items under the broiler.

Avoid sudden temperature changes, such as putting cold water in a hot cazuela, because this can cause cracking.

I've also answered over on the CF Marigene. My Spanish cazuelas are my main cooking utensils and I use them on a low to medium flame with a diffusor underneath on my gas stovetop as well as in the oven. Haven't broken any yet and one is around 35 years old.
I treat them gently though and wash them carefully by hand as I don't have a dishwasher. If stacking them together on a shelf, I put a cloth napkin underneath each one as well.

SharonCb

Thanks ladies. I am going to order more of them and get rid of some of the other casserole dishes I have. I just love them and they clean up so well. They were soaked overnight per the seasoning instructions that came with them, as well as filling them to half an inch of the top and adding vinegar and then simmering them until the water had about evaporated. Whatever the reason for the vinegar, it worked as far as cleaning up.......nothing sticks to them and there is no vinegar taste to anything cooked in them.

I bought 2 cazuelas in mexico and used them this weekend to make mole. I have some burned spots on the bottom where mole burned and stuck and I cannot get it clean. any suggestions??