What is the right course of action here?

In this situation, you want to turn left and there is a cyclist approaching from the opposite direction who wants to go straight. According to German traffic rules, when turning left, you must always yield to oncoming traffic that is going straight, including cyclists. This is for their safety and to avoid collisions. That’s why the correct action is to wait until the cyclist has finished crossing. Taking priority or using your horn is both wrong and dangerous here. Always make sure you let oncoming cyclists go first when you are turning left across their path.