How did the first amino acids appear on Earth?
The universe cooled after the Big Bang. There was certainly an epoch when the universe’s overall temperature decreased from 200 °C to −40 °C throughout a very large volume. There is your test tube (more like a Florence flask) for abiogenesis and then the panspermia reservoir.

Before you suspect the preceding is clever, how and when (what ambient vacuum temperature) did elements heavier than boron arise?