Preheat broiler to medium heat and place rack in the top of the oven.

Butterfly the pork tenderloin by slicing lengthwise down the center, almost all the way through.

Open the tenderloin and flatten it.

Continue slicing and flattening until the entire tenderloin is 1/4 to 1/2 inch thick.

Lightly oil a baking sheet and place the tenderloin cut-side down.

Combine mustard and olive oil, then rub on the pork.

Season with salt and pepper.

Broil until golden brown, about 12-15 minutes.

Remove from broiler and transfer to a cutting board.

Cover loosely with foil and let rest for 5 minutes.

Slice against the grain and serve with salsa verde.