–  Preheat oven to 350 °F (175 °C).
–  Split each tenderloin lengthwise, without separating completely, then spread open and rub lemon over meat. Set aside.
–  In a skillet, melt butter and saute, but do not brown, onions over medium heat.
–  Remove from heat. Add breadcrumbs, sage, lemon peel, salt, and pepper. Stir, then add egg.
–  Spoon stuffing onto a pork tenderloin, cover with the other, tie with string and coat lightly with flour.
–  In a stove-top casserole, melt chopped bacon. Cook pork tenderloins on both sides until golden, cover, then bake for 40 minutes.
–  Remove tenderloins from casserole, place in a serving dish and keep warm.
–  Add 1 tbsp (15 ml) kneaded butter to cooking juice and stir, then pour beef stock over mixture and reduce liquid to half or until the sauce reaches desired smoothness. Pour sauce into a gravy boat and serve with stuffed pork tenderloins.