I posted the other day about visiting Buddha Dendo in the mountains in northern California. On the site there is a new building, a goma-do. This is for the performance of the fire ritual, the goma, that is part of esoteric Buddhism in Japan. You will find it in both Shingon and Tendai Buddhism and also within the Shugendo practices that have connections to both Shingon and Tendai. Most people outside of Japan are not familiar with the Japanese goma ritual. I know of a few people that have witnessed it here in the United States that are not practitioners but most people who see it have to go to a Shingon or Tendai temple (a rare thing here) in order to witness it. (Though I am aware of one instance of a Japanese priest performing the goma at Burning Man as witnessed by a Buddhist friend of mine.)
The goma is ultimately derived from the Vedic homa fire ritual. As many people are aware, but commonly don’t reflect on, Buddhism was originally an Indian religion that developed from the matrix of religious cults (in the proper sense) and philosophies present in India at the time of the Buddha. The Buddha’s teachings were a sharp break with earlier traditions but its practices and the philosophical framework in which it worked were not created from nothing and were influenced by the cultural matrix. While controversial to say for some who hold to a kind of fundamentalism, it is also likely that later Tantric Buddhism was heavily influenced by the non-Buddhist Tantra present in India in later centuries. Traditional or later non-traditional elements of Indian religion were often reinterpreted, especially on an inner level, from a Buddhist point of view.
You can also see a version of the fire ritual within Tibetan Vajrayana Buddhism as well. (I found an abstract of what looks to be an interesting article comparing Tibetan and Indian fire rituals.)
As Dr. Richard Payne notes in his book, “The Tantric ritual of Japan: feeding the gods, the Shingon fire ritual”:
It is well recognized that there is a historical continuity between the goma of present day Japanese Tantric Buddhism and the fire sacrifices known to predate even the earliest Vedas. Elements of the Vedic rituals have been found to be identical with the elements of the Goma.
Later, Dr. Payne goes on to write:
One of the characteristics of Tantric Buddhist goma is the importance placed on the inner goma. The inner goma is a visualization which emphasizes the unity of the deity, the fire and the practitioners (the mouth of the deity, the mouth of the altar hearth and the practitioner's own mouth are visualized as one), and the unity of the three mysteries of body, speech and mind.
You can see a very brief example of a Hindu fire ritual on Youtube.
You can compare it with the very brief bit shown of a Shingon goma ritual here as well.
(People tend not to film these as they are fairly private but the above seems to come officially from a temple on Koyasan.)
The goma ritual is much longer (around 45 minutes or so oftentimes) so this is really just a brief snippet. Unfortunately, you don’t see the pouring of the oils in the Japanese ritual clip as you do in the Hindu one but it is present if you witness the ritual.
In Japan, there are public performances at various times a year with large crowds. I did find one example of this on Youtube as well.
This all seemed worth saying something about since it is far outside the experience of most people outside of Indian and Japanese culture (or Tibetan, for that matter).