Was it difficult to open the can of commercially processed bean dip? What if I can't find that brand in my store? Is it okay to substitute cat food instead? What about the canned olives? Is it okay if I buy a can of WHOLE olives and slice them into slivers, instead of rings, just to kick the dish up a notch...oops, wrong chef.The last time I ate my way across Mexico, I did not see a single olive anywhere in my food. Can I omit them without affecting the authenticity of the dish?