Sapporo offers many different possibilities for lunch and dinner. One of the most famous dishes of the city is the Ramen that you absolutely must taste. There are countless locals preparing it. I recommend you try it in one of the many places you find inside the Station. For a quick oyster snack, head to the Nijo market.
If you go to the city between mid-July and mid-August, you can attend the Sapporo Beer Festival: a beer-themed festival held in various parts of the city where every Japanese manufacturer, and not only them, has its own booth where, in addition to beer, is offered food theme: a kind of Japanese Oktoberfest.
For a different evening I recommend going to Susukino for dinner. If you want to treat yourself well and enjoy a good dinner, in Italian style, I recommend the Osteria Bava. Taste the seafood risotto: a treat!
Finally, you can't miss the chance to taste a dish of grilled Genghis Khan meat typical of Hokkaido. I recommend you taste it in the Sapporo factory beer garden. In this huge room (which used to be the brewery itself) you will seat yourself at a table with a huge cooker in the center where a cast iron grill will be placed on which you will have to cook the vegetables and the lamb meat. Remember to put the "bib" that is provided to you as sketches start from the grill during cooking. It will be a funny and tasty experience to water with a nice mug of Sapporo beer! Kampai!