What was UFC star Brandon Moreno doing when he received the biggest phone call of his life???
Eating a DELICIOUS burger ... of course.
Here's the deal ... 26-year-old Moreno -- the #1 contender in the UFC's flyweight division -- got a big 1st round win against Brandon Royval at UFC 255 last Saturday night.
Moreno -- who had to weigh in at 125 lbs. -- wanted to blow off some steam after the fight ... so naturally, he went to grab a cheeseburger.
Enter the biggest opportunity of Moreno's career .