MIAMI — Now the fat’s in the fire.

Jet coach Rex Ryan, who started the season by challenging Dolphins linebacker Channing Crowder to a fight, flipped off Miami fans at a mixed-martial-arts event he was attending in Sunrise, Fla., over the weekend.

Ryan, in the Sunshine State for the Pro Bowl, was doing a ringside interview with a Showtime reporter piped through the arena. Through a raucous chorus of boos, he delivered one of his bold predictions: “I just want to tell everyone in Miami that we’re coming to beat you twice next year.”

That’s something Ryan’s Jets failed to do in 2009. They were beaten twice by the Dolphins.

Later, as the arena emptied, he raised the middle finger of his right hand at several Dolphins fans while wearing a big smirk on his face.

Yesterday, the larger than life coach, who is known to consume 7,000 calories a day, served himself a helping of crow.

“It was stupid and inappropriate,” Ryan said. “I wouldn’t accept that type of behavior from one of the coaches or players, and it’s unacceptable from me. I apologize to the Jets’ organization, the National Football League and NFL fans everywhere.”

Team General Manager Mike Tannenbaum said, “Rex showed extremely poor judgment, and his conduct was inappropriate. He knows he was wrong, has apologized and we have accepted his apology.”

The NFL said it would “look into” the possibility of fining Ryan. Tennessee Titans owner did the same thing to Buffalo Bills fans in November — and it cost him $250,000.

David M. Hildenbrand, the Dolphin fan who took the picture — an instant Internet sensation — told The Post that Ryan “was walking by us after the event and a couple buddies of mine said some things like, ‘Dolphins rule, Jets suck.’”

“[Ryan] looked at us and said, ‘Go f— yourselves,’ and then he gave us the finger.”

When Ryan flipped the bird to the group, a bunch of fans started shouting things at him like, “Manning whupped you.”

“He was being a smart ass,” Hildenbrand said. “That didn’t surprise me seeing the way he coaches and how he talks.”

This isn’t the first time Ryan has verbally grappled with the Dolphins and their fans.

Last summer, during a Jets mini-camp, Ryan got into a row with Crowder that lasted days.

It began with Crowder responding to Ryan’s bold talk during the off-season by saying that he’s “the OTA Super Bowl winner,” referring to “off-season team activities.”

Ryan fired back: “I don’t know this Channing Crowder. All I know is that he’s all tatted up, so I guess I ought to be nervous about him.”

He also said if he were younger, “I’d probably handle him myself.”

Crowder’s response: “Oh, Lord have mercy. What’s wrong with him? I’d have beat the hell out of that big, old joker.”

Ryan has insisted the war of words was all in fun.

mark.cannizzaro@nypost.com