Fruit chutney is available in most supermarkets. Look for the chunkiest version you can find.
Heat oven to 400 degrees. Rub meat with oil; sprinkle with salt, pepper, and thyme. Roast in a small pan until a meat thermometer inserted into the thickest part of the meat registers 160 degrees. about 1 1/4 hours. Tent with foil to keep warm; let stand.
Place chutney in a small saucepan over medium heat until very warm. Set aside.
Slice rolls open, and spread with mustard. Slice meat into 1/4-inch-thick slices, and arrange over the bottom halves of each roll. Top with warm chutney. Cover with the roll tops, and place on a baking sheet. Transfer to the oven, and heat until rolls are toasty and filling is hot, about 5 minutes. Serve immediately.