I would recommend ordering "blatt salat" as a side instead of vegetables. Blatt Salat is a leafy green salad that is tossed in an olive oil/vinegar dressing. Sometimes it comes with pickled vegetables, but usually very good. You can also order this as a main meal with a protein. Unfortunately, in my experience living here, ordering vegetables hasn't been pleasant or it comes in an herby cream sauce (which is not appetizing in my opinion). If you can go to a store/market and buy the fresh fruits and vegetables, as it's much tastier! In my experience it can be hard to eat out and find what you're are looking for in the winter. The dining experience in the summer time in Germany is much better with tastier options!