Joso the Jawa is a Jawa that has gone into salvage at a more galactic scale. Instead of remaining on Tatooine and scrounging up items for repair and sale he got a job with a salvage ship and went off to make his fortune among the stars.
Eventually Joso the Jawa ended up earning enough credits that he could buy his own ship and pay his own crew. He became took salvage contracts through the company he worked for and started to salvage older battlezones. The more time that passed between battles the less scrap there would be, but there would also be more safety.
After doing this for a long time the crew of the Sandflier (three guesses as to why it was named that) were itching for a little more excitement. Sure, they were making money, but the job was routine and boring. Joso the Jawa decided at this point to go in immediately after the conflict and salvage as much as possible before turning tail and running. This is how he ended up saving a Jedi by destroying two of the three Sith ships attacking her.
The crew was reluctant to get involved at first, but that became moot as Joso the Jawa flew the ship into the battle and forced the crew to stations or death. After the battle they were able to fit the starfighter into the cargo bay, then re-pressurized the bay to allow the Jedi to exit the fighter. Tate (T8-T3) was acting as the mechanic in the starfighter and started to interact with the crew. Tate and Joso the Jawa became fast friends and would have many interactions following this initial encounter.