The best cheeseburger in Berlin costs less than 5. Burgermeister is mandatory in town when you're craving for a basic and delicious to the bits chesseburger. 

Cosmoveda is a hidden xberg gem. It's an Ayurvedic supermaket that happens to come with a kitchen with it. There you can find a delicious Ayurvedic lunch menu (with soup, main and a little dessert) in 3 different sizes, prices starting at just 5,90. Not to mention you can shop the ingredients that you just ate in case you want to try to cook Ayurvedic yourself.  

A good place to drown your Berliner winter-melancholy. The bartenders are top notch and the interior is warm but stylish, with the inevitable retro vibe. Open from 6 till late. There´s also a legendary (and kinda expensive) restaurant next door, which provides the bar with some excellent snacks. Works for dates and for friends, but if you´re planning for a bigger group it might be wise to reserve.

Little Vietnam in Berlin - crazy crowded market halls stuffed with commodities from overseas.

Soluna bakery is where I get my (delicious) bread.