The staple for me at Simit & Chai is the vegan simit. Loaded with cucumber, fava bean and olive paste, it's reasonably priced for the area at about $6.
If you like sweets, their ?ekerpare, a dense cookie soaked in honey, is worth trying too. I love the moist and crumbly texture. As for drinks, I've only had the Istanbul Fog, but the drink felt more standard and was not particularly a standout for me. Either way, this is a comfortable spot with decent food to spend some time at.