type of beef selection

I’m making an appetizer for 150 people for a fundraiser. The recipe calls for using “beef fillet steak 3/4” slice" per serving. I’m looking for help as to the best cut of beef that I can use, keeping cost down tenderness needed. Each beef slice is cut into a steak round using a pastry type cutter. The receipe is called "BROILED BEEF FILLET W/SALSA VERDE CROUTES. I hope you all can assist me. TU

I would like to have this recipe if you would be kind enough to share it.