The Rotkehlchen is a sweet little Café/Bistro located in the Ehrenfeld area close to the local train and also subway station.
Their menu offers both meat and vegetarian/vegan options (full meals, cakes, cupcakes), and all beverages can be ordered with dairy free milk. They don't always have vegan cakes, but the cupcakes usually make up for that!
The location itself is beautifully refurbished and very inviting. Make sure to check their merchandise (Turnbeutel!!)!
Cons: sometimes only few vegan options