Brock Lesnar -- Rebounds From Stomach Illness ... CRUSHES Italian Food

Two years after UFC badass Brock Lesnar was forced to retire due to serious stomach issues, the Beast Incarnate proved his guts are still TOUGH AS HELL ... by woofing down enough food to feed a small Italian village.

As you may recall, Brock was diagnosed with a severe case of diverticulitis back in 2009 -- a digestive tract disease that usually forms in the large intestine -- and after multiple surgeries, he was forced to retire in 2011.

But things are lookin' up ... 'cause TMZ has learned Lesnar and his wife Sable hit up Fresco restaurant in Montclair, NJ on Monday ... and Brock put his belly to the test.

Check out what he ate:

-- Ahi tuna with asparagus (shared)
-- Margherita pizza (shared)
-- Chicken Parm ... with TRIPLE-EXTRA chicken
-- Full bowl of parpadelle bolognese

... and, to top things off, dude crushed a slice of cheesecake by himself.

We're told the entire meal cost just north of $500 ... PLUS, we're told the WWE star left a "very generous" tip to everyone who stayed past closing time to take care of him.

Awesome.