I made this earlier in the week and it was fabulous. (I used tenderloins that were about 1/2 pound each, and the cooking time for these was about 25 minutes...best to use a meat thermometer so you don't overcook them, it's easy to cook them too long and end up with dry meat)..
After soaking venison in salted water, removing all gamey taste, place in fridge covered with mixture of olive oil and 5 cloves mashed garlic (a bit of rosemary doesn't hurt either). Let marinate in oil/garlic mixture for at least an hour.
Preheat oven to 525° F. In a medium-sized mixing bowl, combine parsley, rosemary and thyme. Add garlic, cracked black pepper, Dijon mustard, breadcrumbs, Worcestershire sauce and water. Stir to make a thick paste. Spread paste over loin. If necessary, tuck thinner end of loin underneath so that it will cook evenly. Salt and pepper to taste.
Place loin on oven roasting rack inside of oven roasting pan. Place in oven and reduce oven temperature to 375° F. Roast until meat thermometer reads 125° F for rare, 135° F for medium-rare (temperature will continue to rise a few degrees after pulling from oven). Do not cook past medium-rare. (My experience showed that if you're using smaller cuts of loin, cooking time could be as little as 15 minutes-learn to know your meat by touch or buy a thermometer)
Remove and let sit for 10 minutes before carving. Slice thinly against the grain.
Mix Creamy Horseradish Sauce ingredients together and serve aside the loin. YUMMMM!