Don't go to the cafés that are right by the water in Plateia Aristotelou or even along the waterfront on Nikis. They're ridiculously overpriced given that the coffee they serve is usually not all that good. If you want something better, concentrate on the the cafés along Aristotelou that are closer to the Roman Agora, north of Tsimiski. The prices are lower and the coffee they serve is usually better (i.e. stronger hehe).
Favorite Dish: FRAPPE! I think I developed a serious addiction in Thessaloniki.
Take a walk in and around Thessaloniki city market. You'll see lots of restaurants and cafes here. I personally recommend those in which locals dine.
In the market hall a some of small restaurants can be found serving local specialities at reasonable prices. Often you can chose from variety of seafood to be cooked for you.
When you are walking along D. Gounari street towards the Rotunda of Saint George, just before you reach it, you'll see a small unassuming tavern to your left. It advertises fresh (& mainly grilled) seafood and if you love fish as much as I do, you must not miss it.
Also, if you go in any local tavern, don't miss souvlaki (grilled meat pieces on skewers; lamb is the usual meat for Greece) and uzzo or retzina (alcoholic drinks which you either hate or love).
Favorite Dish: Grilled small octopus and calamari.
All of the restaurants (koutoukia) in Athonos square and also ÂáóáíÜêéá (pronounced 'Vasanakia') behind the cinema Radio City'. One of the most strange restaurants is Ïýæïõ ÌÝëáèñïí (pronounced 'Ouzou Melathron') near Venizelou str. It has the most strange and delicious meals. Take a chance.
But if you walk for a while in the city it´s certain that you´re going to find a good restaurant to eat good food (there are so many).
Favorite Dish: A bit of everything (mezes) with wine or ïýæï (ouzo) or beer!! (almost in every restaurant).
Actually, Tzinari is not a restaurant. It's an area that you can find a lot of tavernas and restaurants. Most of the tavernas there are very old and they have delicious food.
99% of the taverns and restaurants in Thessaloniki offer top quality food. I prefer the nonstandard greek cuisine of 'plateia Athonos' and 'Beer acdemy' beer house (pic). The best chinese restaurant among all chinese restos i had lunch all over europe and canada is in thessaloniki ('Peking' at sofouli street) - update - not any more they changed their cook...pity!!!!!
The tavernas located in the city center near the Agora.
There are so many people eating here and everyone is enjoying life together.
Favorite Dish: Mezes. These are small plates of delectable Greek appetizers. I recommend that you drink Tsipouro with your meal, which is the local drink of Northern Greece. Tsipouro is similar to Ouzo, but not as sweet nor as anise-seed flavoured, it is strong, smooth and ideal with the food.
Forget usual restaurants, try as many ouzery as you can; they serve mezedes (similar concept as tapas bar in Spain) with ouzo wich is a strong but tasty greek liquor ... amazing. My best: Melathron for the evening.
For the afternoon (yes, it is not so common going for lunch at noon) Aristotelus is the best place IMHO; it is an ouzery few steps away from Mr. Aristotelus himself seated in his own square. Be careful: they have a small entrance between two adiacent buildings, not so easy to find it out if you're distracted :-)
And now the most romantic one: Hamodrakas in Kalamaria (few kilometers away from Thessaloniki heart), wonderful seafood and impressive sightseeing while dining; when seated you are at less than one meter from the sea (which is always polluted anyway but, you know, it's dark ;-).
Hamodrakas is perfect for a romantic dinner ...
Favorite Dish: Seafood, almost everywhere ...