Preheat oven to 400 degrees F. Mix the tarragon, jelly, and mustard together. Season the venison with salt and pepper. Pan-fry the seasoned venison in the butter until golden brown on 1 side, about 4 minutes. Turn the venison over and put in the oven for 5 minutes. Remove from the oven and turn the oven on broil. Slice the venison horizontally and open it like a book, spread the jelly mixture on both sides. Brown top under broiler for 2 minutes and serve.