Bobby Flay -- Looking for New Home to Cook Dinners for One

Bobby Flay just gave a big clue why his estranged wife is so angry about their prenup ... because he's looking for a new place to live that costs millions and millions of dollars.

We're told Flay was on the hunt Monday for a bachelor pad in the Sterling Mason building in the Tribeca. There are 4 units available, ranging in price from $9.65 million to $24.5 million.

The building's so fancy it has a library lounge, courtyard, a private fitness room (with yoga studio, of course), a children's playroom and, remarkably for the area, an underground parking garage.

Flay and wife Stephanie March separated last month, and he pulled the trigger on divorce papers last week.

He looks ... pensive.