Preheat oven to 450°F

In small bowl, stir together mustard, sour cream, ginger, thyme and pinch of salt; set aside

Make several 1/4 inch slits in tenderloin.

Slip garlic into slits.

Brush tenderloin with oil and season w/ salt and pepper

Heat a large cast-iron or other ovenproof frying pan over high heat

Add tenderloin and brown on all sides, about 5 minutes. Remove pan from heat

Spread mustard mixture over pork, then transfer the frying pan to the oven and cook about 30 minutes until 150°F in center.

Remove pan from oven and transfer pork to cutting board; loosely cover with foil and let rest for 5 mins before slicing. Serve warm or at room temp.