For the tenderloin skewers: Cube the meat into 2-inch pieces and skewer with rosemary sprigs. Place in a shallow dish and set aside.
In a small bowl, whisk to combine the olive oil, light brown sugar, Worcestershire sauce, mustard powder, cumin, salt, pepper, garlic and lime juice. Pour the marinade over the meat, making sure to coat all the pieces. Cover and let marinate for 30 minutes.
For the mustard horseradish cream: Meanwhile, in a small bowl, stir to combine the sour cream, horseradish, mustard, salt and pepper.
Heat a grill for cooking over medium-high heat. Grill the skewers until cooked through, about 1 to 2 minutes per side. Serve with the mustard horseradish cream.