"Mangio una bistecca al pepe."
What's a pepper steak?
And why isn't "I eat a steak with pepper" correct?
Pepper steak is just a steak that's coated with pepper before cooking. There is a difference between that and a steak which you have peppered at the table, but it is an oddly specific dish to be teaching this early in a course.
Not sure what pepper steak is. but "I eat steak with pepper" would be "Mangio una bistecca con pepe." 'con' meaning 'with'