The Chalet at the Hotel Chalet-Oberland is one of my favorite restaurants in Interlaken. It is conveniently located on the main street and you can just drop in without worrying about reservations. The decor is Swiss.
The menu has a wide variety of choices of mostly Swiss/German type dishes. You can get fresh fish (caught locally) and venison, as well as pork, beef, and chicken dishes. Most meals are served with noodles or potatoes, but there are many more vegetable choices. We equate Switzerland with fondue and this is the place for it. The cheese fondue with bread was wonderful. Servers are very courteous. The next time I am in Interlaken, this is my first choice in restaurants.