You write that you eat in a restaurant with a hechsher of the local rabbinut - but only for pareve items which have no problem of prohibited food mixed in. Your claim that you have verified that in your location they are careful not to have bishul akum. You say that you take teruma and maaser yourself and you don't eat foods that require careful examination for worms and other things. Answer: I am surprised by what you write. Don't you know that the rabbinut relies entirely on the Israeli identity card to determine if a person is a Jew regarding bishul akum? This is problematic since there are hundreds of thousands of Israeli's who came from Russia and the Israeli government considers them Jewish based on an invalid conversion since it is know that they were not committed to keep the mitzvos when they converted. Or they are given a Jewish status simply because it was claimed that someone in the family was Jewish. It is sufficient for the Israel government that someone claims that a grandmother lit Shabbos candles or they are taught to lie and simply claim that they are Jews. Others have forged certificates that they obtained in Russia. In addition there are immigrants from all over Europe who received the right to immigrant according to the Law of Return based on questionable status as Jews or converts. Then there are 150,000 Ethiopians that the Chief Rabbi declared to be Jewish without conversion when in fact we regard them as non-Jew or at least possible non-Jews. Nevertheless all of these problematic cases have Israeli identity cards saying that they are Jews. In addition they rely on poskim that say that Shabbos violators do not have a problem of bishul akum, while major achronim state that they do in fact have a problem of bishul akum....There are other problem such as the view of the Chazon Ish that food produced in the factory of a non-Jews or someone who is not observant is prohibited because of bishul akum. The Shulchan Aruch and Gra rule that even if a Jew lights the fire, but if a non-Jew puts the pots on the fire – it is prohibited because of bishul akum. In particular in our case where the restaurant it owned by Shabbos violators who have the status of non-Jews and thus it is like the house of a non-Jew and therefore it is not sufficient that the mashgiach lights the fire.... We see clearly that there are many halachic concerns. In addition there is the view of the Taz mentioned in the Darchei Moshe that it is prohibited to eat even permitted food from a problematic Jew because he might feed you something which is prohibited... Thus we should avoid eating in such restaurants. A person who avoids sin even in private is called someone who sanctifies G-d's name. This is explicit in the Rambam (Hilchos De'os 5:10), All those who avoid sin or do a mitzva – not because that is the way of the world and not because of fear or awe or desire for honor – but for the sake of G‑d as Yosef avoided being with his master's wife – this is kiddush HaShem. Consequently from now on you should avoid eating in that type of restaurant or similar situations. In particular because when people see you eating there they will assume that there is nothing wrong to eat there and thus you will lead others astray.