Stephon Marbury's Ex-Mistress -- Give Me Hush Money or Give Me Benz!

Stephon Marbury's ex-mistress is hell-bent on collecting her hush money from the ex-NBA star ... even if that means going after his precious assets, like a couple of luxury cars.

TMZ broke the story ... Marbury and Thurayyah Mitchell -- the personal chef he boinked, while he was married, back in 2006 -- had an agreement: she would keep quiet about the affair, as long as he coughed up $900,000.

Problem is ... Marbury stopped making payments around the $600,000 mark, so Mitchell dragged the NBA star to court earlier this year, where a judge ordered him to pony up the remaining $331,584.50.

According to new court docs ... Mitchell claims Marbury still hasn't paid, so she wants a judge to force Marbury to turn over his Mercedes-Benz, his Land Rover and liquidate some of his assets to settle the debt.