What is required of me after eating what is believed to be pork in a foreign country, especially since the restaurant is known for serving pork?

If you know or strongly suspect that the meat is pork, it is not permissible for you to eat it, and you must avoid it. If you have eaten it, you must repent and seek forgiveness. However, if it is merely a possibility, the general rule is that it is permissible to eat the food of the People of the Book, though piety dictates leaving what makes you doubt.