Jewish Corned Beef
It's not clear to me whether you want a restaurant type of deli, or a place where you can buy deli products. Kosher corned beef (Hebrew National---sorry, it's not homemade) and other kosher deli meats are availabe sliced to order at the Stop and Shop at Vinnin Square in Swampscott, on the Salem Line. You might find them in the Beverly and Danvers stores as well. If kashruth is a concern, try Levine Kosher Meats on Lowell Street in Peabody. He also has some prepared foods.
There was a kosher-style take-out deli in Peabody for many years. About two years ago, the owners moved to Swampscott and tried to run a deli/restaurant. They never learned how, and closed after about a year and a half. A lot of people were rooting for them and it was too bad that they failed.
Hi Janice Jewish deli is a tough category these days. I am not sure why but not many good ones are left. Since the "old Goddfrey's" (before the re-model) closed, I don't know of anything up on the North shore. You may want to stop in at Karl's Sausage Kitchen 142 Broadway (RT#1) Saugus 781 233-3099. I don't think Mike has corned beef but Karl's is certainly worth a visit. Mike makes many of the things that they sell. Bologna, Bratwurst etc. and the not to be missed "hot dogs". The place is immaculate with everything lined up perfectly. His kitchen is-Operating Room-clean. Maybe they can recommend good corned beef in the area. Sorry we couldn't be of more help. Usually we do better. Keep posting!