Final answer:
Alexis introduced herself as Sapphire to Lisa Chung, which was a significant encounter for Alexis.
Step-by-step explanation:
The name that Alexis gave when she introduced herself to Lisa Chung was Sapphire. This introduction took place after Alexis had come out in San Francisco in the spring of 1975, at a time when she believed there were no other Asian lesbians in the area. It was a significant moment for Alexis because she had heard of someone named Sapphire but had not met her until a chance encounter when Sapphire arrived in a large car looking for someone named Kate. The meeting left a profound impression on Alexis, particularly because she found Sapphire's beauty captivating.