The Aussie bombshell doesn't hold back in this latest getup Sunday ... serving up some serious heat in a super sheer black ensemble with thin clear straps that were fighting for dear life trying to contain her assets.

Bianca's confidence in rocking her daring styles is iconic ... but even she knows when to draw the line 'cause she strategically placed her phone across her crotch to keep things R-rated -- as opposed to NC-17.

Of course, Kanye's outfit was nowhere near as shocking, but he did match his wife in an all-black look for the outing that saw them reunited after a brief break.

BTW, worth noting ... Ye is rocking Nike gloves here -- telling, considering his on-again-off-again feud with Adidas ... with whom he's currently on the outs as he's accused them of trying to make money off his Yeezy designs. What else is new though?

One last thing about this little outing of theirs in the Valley -- some dude tried blocking them off as paps fired away ... throwing up what appeared to be a jacket or blanket of some sort as he aggressively tried to obscure their view. No word on whether he's a hired security guard, or just some random Schmo who popped up out of nowhere. It's kinda giving the latter!

Anyway, it's clear Bianca isn't shying away from her typical style these days -- even with her folks in town ... or one of them at least.

As we reported ... BC was hanging with her mom, Alexandra, for the last few days ... hitting up Rolling Loud to catch Ye's performance and stopping by a San Fernando Valley cosmetics store. In the latter, the model went braless under a pink mini-dress -- but for the most part, it was practically conservative dressing on her part.