Buddhism and past lives? The idea of having more than one life in Buddhism is regarded not  just as a theory but  a truth that can be experienced and verified If this is so, what was the technique used by the Buddha to recollect past lives? What is the exact technique that leads to remembering one's past lives according to Buddhism?
According to my teachers (Korean Zen and Tibetan Vajrayana), because Buddhism explicitly denies existence of soul (see anatta), the concept of rebirth does not refer to reincarnation of the same person, but rather to propagation of information from one life to another.

Recollection of past lives then is not to be understood literally but as a metaphor for clearly seeing patterns of karma acting out from one generation to another. This requires shedding an irrational belief in existence of "I" as a solid entity, subject of experience, and independent agent of action.

The technique for achieving this level of insight is known as vipassana or "special insight meditation", to be preceded by "calm abiding meditation", samatha, in order to attain the necessary clarity of mind.