Pity Angela Montgomery, a 30 year old in Sterling Heights, Michigan, who is suing the restaurant chain Denny’s after finding bacon in her vegetarian omelet.

The lawsuit describes Montgomery as a “practicing Jew whose religion forbids the eating of any pork product.” She said she felt “poisoned” by the inappropriate addition to her breakfast. The waitress and restaurant manager apologized and offered a replacement omelet free of charge, but Montgomery had lost her appetite by then. She left the restaurant, sick at heart and possibly with a misery-induced stomach ache as well. Her lawsuit followed a few weeks later.

When I first read about this lawsuit, I wondered: Did she really think she was going to eat a kosher omelet at Denny’s, a decidedly non-kosher restaurant?

But then I remembered how many of my Jewish friends and I growing up thought we were keeping kosher by not mixing meat and milk, avoiding shellfish and shunning pork. Like Angela Montgomery, we were sincere in our desire to keep kosher, we just didn’t know all the dietary laws and what it really meant to eat kosher. Our heart was in the right place, but now I realize “kosher style” is not the same as truly kosher.

So we comfortably kept quasi-kosher, careful to avoid overt manifestations of pork or other treif food. Like Angela Montgomery, we endured some upsetting surprises. Asking about what appeared to be a mushroom salad in a Chinese restaurant buffet that one friend was munching away on, the waitress explained she was in fact eating pig ear salad.

After I moved away from home and started cooking for myself, I soon discovered that sautéed spinach, one of my favorite dishes, is tasteless and bland on its own; much of its flavor comes from the addition of chicken or some other soup. Butter, meat stock, cream - all sorts of ingredients are routinely used to enhance the taste of even simple-sounding dishes.

Some popular types of fish, like red snapper, are often mislabeled. All those years my friends and were ordering kosher-sounding fish, what were we being served instead?

Some of us looked for a “K” printed on food products, even though a K by itself means nothing (kosher signs are always a trademarked symbol such as the Orthodox Union’s clearly identifiable U inside of an O). We assumed that foods that didn’t clearly list “pork” or other non-kosher ingredients were kosher.

We couldn’t have been more wrong.

Turns out that gelatin (unless it’s specifically kosher gelatin) often comes from pork. So does the key ingredient used to make non-kosher cheeses. Many brands of wine contain additives made from fish bladder, gelatin, milk, even clay and charcoal. (At least those last ingredients aren’t non-kosher, though they’re not exactly food either.)

Non-kosher marshmallows contain pork. Some red food dyes are made from insects and some purple food dyes are made with shellfish. The shiny shellac on lollypops and hard candies comes from secretions of the female lac bug, commonly found in Southeast Asia.

Stearic acid, which makes non-kosher chewing gum soft is sometimes extracted from the fat of dogs, cats, pigs, sheep and cows. The common ingredient L-cysteine, used to soften bread, is derived from hog hair, duck feathers, or human hair. Castoreum, an ingredient in many ice creams, is made from the anal glands of beavers.

The more I learned, the more I wanted to see the reassurance of a kosher sign on my food. Eventually, my family and I switched to keeping fully kosher. And when we eat at our favorite kosher restaurant, we can be sure we won’t have an unwelcome bite of pork in our vegetarian omelet.

Click here to read The ABCs of Keeping Kosher.