In a skillet, heat 1 tablespoon of the oil over a medium heat. Add the onions and cook until onions have softened about 7 to 10 minutes. Stir in the red peppers and sour cream, and continue to cook stirring until heated through and bubbly. Transfer the pepper mixture to a blender or food processor. Add the seasoning mixture and process until smooth.
Preheat grill or broiler.
Grill the pork for 5 to 7 minutes on each side until internal temperature reaches 160ºF.
Let meat rest for 5 minutes covered before slicing. Serve the sauce over the sliced tenderloin.