No.57 on the Top Floor of GUM
This is a highly recommended place in various guides. It's a self-service restaurant where you pick your food and pay at the end. A small tip: don't take too many sweets. Each dish at No.57 has a straightforward Chinese translation.
tepemok
This is a nationwide chain restaurant in Russia where you can buy reasonably good Russian fast food.
Goose&Goose
This is an Italian bistro located on a cross street off Nevsky Prospekt, and the food is quite good. For me, the menu filled with food ingredients was really hard to understand, so I basically asked the English-speaking waiter to recommend something from each category. When paying the bill, I tried a bit of Russian and added '...is that right?' The waiter seemed to suppress a smile and nodded slightly.
Delicious and affordable, the soup is ready-made and doesn't require waiting. The pasta is made to order and requires waiting. I recommend the creamy cheese bacon pasta, it's very tasty. The borscht is also very good. The roasted vegetables are tastier than the raw ones. The salmon is relatively expensive and, in my personal opinion, tastes average.
This is also a fast food restaurant that can be found all over the streets of St. Petersburg. You can have coffee, a burger, or a pancake, buy a dessert, and sometimes encounter incredibly beautiful girls. They are so beautiful that you can't even complain about why God closed a door for you... Compared to them, God never even opened a door for you... I bought a stack of postcards and sat in a Coffee House on Nevsky Prospekt, writing and eating, eating and writing, wasting a lot of time...
Oliv'ye
On the last night, I tried this restaurant that had Russian & Caucasian cuisine written on the signboard. The waiter spoke English. Surprisingly, the dishes did not disappoint me at all~ Every dish was delicious~ Highly recommended with five stars.