You know you can’t eat meat on Fridays in Lent, but what about soup made with chicken stock or sauce made with meat? The USCCB answers this question on a Lent Q&A page:
Q. I understand that all the Fridays of Lent are days of abstinence from meat, but I’m not sure what is classified as meat. Does meat include chicken and dairy products?
A. Abstinence laws consider that meat comes only from animals such as chickens, cows, sheep or pigs — all of which live on land. Birds are also considered meat. Abstinence does not include meat juices and liquid foods made from meat. Thus, such foods as chicken broth, consomme, soups cooked or flavored with meat, meat gravies or sauces, as well as seasonings or condiments made from animal fat are technically not forbidden. However, moral theologians have traditionally taught that we should abstain from all animal-derived products (except foods such as gelatin, butter, cheese and eggs, which do not have any meat taste). Fish are a different category of animal. Salt and freshwater species of fish, amphibians, reptiles, (cold-blooded animals) and shellfish are permitted.
To conclude – you can eat fish, butter, eggs, cheese, and even soups or gravies made from meat. You can read the entire Fasting & Abstinence Guidelines here.