EXCLUSIVE

"Iron Chef" Bobby Flay cooks his steaks medium rare ... but his marriage is well, done, and divorce is right around the corner.

Sources close to the couple tell TMZ ... Bobby and his wife, "Law and Order: SVU" star Stephanie March, separated 3 weeks ago. Flay moved out of their NYC home.

We're told both have hooked up with attorneys ... and divorce talks have started.

The marriage has been deteriorating over the past year-and-a-half. We're told things reached a boiling point last year when Bobby didn't come to the hospital until the day after Stephanie's appendix burst. She was livid when, she claims, he said he was busy with work and had to leave before she was discharged ... but offered to send his assistant to help out.

Bobby and Stephanie celebrated 10 years of marriage in February ... only not together. We're told Flay spent the time in Florida at a wine festival with his 'B-Team' -- his group of assistants.