When I go out to eat and I'm not sure what is in it - I consider it a 40 carb day. I just say OK, THIS IS NOT LOW CARB and deal with it.
I had chicken breast with a sauce and now that i look back on it, it may have had cornstarch in the sauce (although they claimed it was made from wine). If it is a midday meal, I have no more carbs for the rest of the day but I make sure I consume a couple tablespoons of flaxseed for the *regularity issue.*

All my tomato sauce in the house has like 10-14 grams of sugar per 1/2 cup. Restaurant sauce is likely to be the same - they want you to enjoy your food with all the high carbs and come back next week for more!

If the chicken was deep fried, it was likely deep fried in partially or fully hydrogenated oils and that will stall your ketosis (as Atkins says) because your body doesn't know what to do with this foreign oil. I'm not sure how long the stall lasts (maybe a day until the body can process it and remove it as best it can).

All things considered, you did well missy!