Final answer:
The portal described in the question is known as an iwan, which is a vaulted hall open at one end, commonly found in mosques and facing the central courtyard.
Step-by-step explanation:
The large vaulted portal opening onto the central courtyard of a mosque is known as an iwan. It is typically a rectangular hall or space, vaulted and walled on three sides, with one end completely open. In traditional Islamic architecture, iwans were used in a variety of buildings but are notably known in mosques for their function and grandeur. The iwan facing the qibla wall, which is the direction that Muslims face when praying towards Mecca, is often the most prominent.
In the context of mosque structures, the mihrab is a niche in the qibla wall that indicates the direction of Mecca, the minaret is a tower from which the call to prayer is announced, and the madrasa is an educational institution. However, the specific feature described in the question relates to the iwan, which could be adorned with colorful tile decoration and often features muqarnas—a type of decorative corbelling used in Islamic architecture.