Osteria Sippi is an incredible simple italian restaurant where everyone feels immediately at home. They not only know their food game but have also an impressive range of really good wines.
A place where I spend some time almost everyday is the Marheineke Markthalle on Bergmannstraße in Kreuzberg. It's just around the corner from where I live and a great place to buy fresh food and products from local farmers or all kinds of delicatessen from different countries. Many market stalls also sell freshly prepared food and it's always busy at lunchtime. For saturday mornings try the original french croissants.
While strolling around Mitte, check out the flagship store of Berlin´s cult women fashion brand. (And try a delicious cinnamon bun at Zeit für Brot next door.)
It is a fine dessert dining. Unique full-on experience with dessert (no industrial sugar is used) course menu and pairing drinks. No wonder they have got a Michelin star!