Beefamato sandwiches are not a Minnesota staple. They’re a regional specialty of Rochester, New York—specifically associated with Nick Tahou Hots (home of the "Garbage Plate") and a few other local spots.
The sandwich typically features beef, tomato, and a distinctive spiced meat sauce on a roll. It’s not widely distributed outside Western NY.
If you’re in MN craving one, you’re likely out of luck unless a transplanted Rochester native is cooking it at home.