1. Preheat oven to 400 degrees F.
2. In a large saute pan over medium-high heat, toast the mustard seeds until fragrant. Using a mortar and pestle lightly crush the mustard seeds. In a small bowl combine the mustard seeds and the panko.
3. Using 2 tablespoons of the olive oil rub the pork and season on all sides with gray salt and pepper, to taste, and roll in the panko mustard seed mixture to coat the tenderloins all over.
4. In a large saute pan heat the remaining 4 tablespoons olive oil until hot but not smoking, add tenderloins to pan and sear on all sides, about 5 minutes total. Move pan with pork to the oven and cook until a meat thermometer reads 155 degrees F, about 10 to 12 minutes.
5. Remove pork from the pan and let rest on a cutting board for about 5 minutes. Slice the tenderloins against the grain on a diagonal bias, fan out on a plate, and serve with the Mostarda di Frutta.