What were the Buddha's meditation methods and practices during his pre-enlightenment wandering years in India?

I am not clear about one important phase of the Buddha's life: when he was a wandering aspirant, after leaving his two earlier teachers of yoga. There is not much reliable information available about how the Buddha conducted his practices of meditation and thought control. The best I know is some fragment of a text wherein the Buddha talks about how he sought to control his thoughts by jamming his tongue to the roof of his mouth. At best, that description sounds like a struggle, not a practice or a method. Is there any sermon where he talks about his struggle? Or a sutra which gives an account of his efforts? Can you throw some light? Thank you.