Here's Bruce Winter on the subject from his book "After Paul Left Corinth" (see especially the portions highlighted in yellow):
pg. 288 "Josephus records an official decree which involved provision of kosher food and which was issued on the resolution of the magistrates from the city of Sardis in Asia Minor and passed by the Council of the People. It was dated after October, 47 B.C., not long before the founding of the colony of Corinth in 44 B.C. (Ant. 14.259-61). This was not the first discussion of Jewish rights in Sardis, for Lucius Antonius, the proquaestor who deputised for Minucius Thermus, the Proconsul of Asia on his recall to Rome, wrote an official letter to the magistrates, the council, and the people of Sardis indicating that the ancient customs of the Jews in that city were to be respected. These included their own 'association', 'a place of their own'---presumably a synagogue--and the right to decide their own 'affairs and controversies with one another' (Ant. 14.235). This letter, written earlier than the decree of Sardis in 47 B.C., appears to have been the catalyst for securing recognition of their ancient customs.
The preamble of this decree began with the customary 'whereas'...in order to explain the context of the official resolution of the Council and the People:
'Whereas the Jewish citizens living in our city have continually received many great privileges from the people and have now come before the Council and the People and have pleaded that as their laws and freedom have been restored to them by the Roman Senate and People, they may, in accordance with their accepted customs, come together and have a communal life and adjudicate suits among themselves, and that a place be given them in which they may gather together with their wives and children and offer their ancestral prayers and sacrifices to God...'
The official resolution then declared, 'it has therefore been decreed by the Council and the People...that permission shall be given to them to assemble on sacred days, to do things in accordance with their laws, and also that a place shall be set apart by the magistrates for them to build and inhabit'. The decree concluded, 'so that the market-officials of the city...shall by charged with the duty of having suitable food for them [the Jews] brought in'...for sale in the marketplace, over which they had control.'"
pg. 296 "The Christian Jews, on the basis of Gallio's ruling [Acts 18], were entitled to purchase meat that had not been offered to idols in the marketplace. Even if the Jews were unhappy with that arrangement, they could not move against the sale of 'suitable meat' to Christians. Gallio's ruling was that the Jews' case against Paul was about an internal religious dispute, 'questions about words, and names and your own law' and not some criminal offence (18:14-15). Therefore the officials who governed the meat market might have been involved. Christians were entitled to purchase kosher meat there, and this may have been the reason that Paul needed to provide no tradition on the purchasing of idol meat for the Christian community in Corinth while he was there. If this was the case, then Corinthian Christians had been able to follow the Jerusalem Council's decision concerning food offered to idols (Acts 15:23-29)--a decision that could only be implemented in Gentile cities where kosher meat was available in the official market."