Donald Trump Learns to Make McDonald's Fries at Campaign Stop in Pennsylvania

Donald Trump's learning the recipe to success ... not in business or politics, but behind a fryer -- getting the secret to McDonald's fries from real employees.

The former POTUS stopped by Feasterville-Trevose -- a rural area just north of Philadelphia -- for a campaign event ... and, he got his hands down in the grease with some of the locals.

Check out the clip ... DJT standing around, waiting for the fries to cook completely -- asking questions to some of the employees there about how they enjoy working at the joint and how the manager treats them.

Trump tells the workers he's got plans to go to the Pittsburgh Steelers game later in the day -- they take on the Jets in Pittsburgh tonight -- and asks questions about the proper way to cook the fries.

Trump handed out food to cars in the drive-thru ... chatting up the drivers while handing out the fast food staple. He dressed for the occasion -- apron on over a white shirt and red tie combo.

We know several members of the media picked up food and yelled questions for Trump ... and, he even used the opportunity to take on Kamala Harris' work history -- saying he's now worked 15 minutes more at the restaurant than the VP.

ICYMI ... Trump's taken aim at Kamala's claim she worked at Mickey D's back in the day -- claiming she's fabricating 'cause she's "Lyin' Kamala."

Tons of Trump supporters came out to show their love for the Republican nominee -- and, he's now got the secret to a beloved fry! Obviously, secret service protocols were in place to protect the former prez.