The Tuohy family says before Michael Oher made "outlandish," "hurtful" and "absurd" claims about them in court on Monday ... he actually tried to shake them down for $15 MILLION.
Marty Singer -- the Tuohy family attorney -- said it all happened recently ... and, what's worse, he claimed this is not the first time Oher has done this.
Singer -- in a lengthy statement to TMZ Sports -- said Oher came to the Tuohys prior to filing his 14-page petition in Shelby County, Tenn.