Slice the filet into 1 cm slices and season with salt and pepper.
Mix the mayonnaise and grainy mustard together.
Heat olive oil in a pan, and fry the pork slices until slightly browned.
Brown the other side. Don't cook the meat all the way through.
Line up the partially cooked pork slices on a grill (fish grill, oven grill, etc.), brush with the mustard-mayonnaise sauce and grill over medium-low heat until browned. (I browned them a bit too much here...)
Done! Serve with vegetables of your choice.
Story Behind this Recipe
I bought cheap pork filet, but didn't want to bother turning it into fried cutlets... but if you overcook it, it turns dry and tough. So I cooked it with a mayonnaise marinade!
When pan frying the pork, brown over fairly high heat. The meat doesn't have to cook through at this point, since it will continue cooking on the grill after brushing with mayonnaise sauce.