1. Preheat oven to 325° Fahrenheit (162° Celsius, Gas Mark 3).
2. With a small sharp knife, make nine small slashes in tenderloin and pocket a bacon strip in each slash.
3. In a large saucepan, melt butter over medium-high heat and add tenderloin, turning to brown on all sides.
4. Carefully transfer tenderloin to a roasting pan and set aside.
5. Add 1/2 cup of water to buttery juices in saucepan, sprinkle seasonings (allspice, black pepper, salt, thyme), and bring to quick boil, stirring regularly and scraping sides and bottom of pan to integrate browning remains into solution.
- Pour seasoned browning solution over tenderloin in roasting pan.
- Add bay leaves.
- Sprinkle tenderloin with another round of seasonings.
6. Set roasting pan in oven and roast for 1 1/2 hours, until tender.
7. Turn off oven, remove roasting pan from oven, and transfer tenderloin to serving platter.
- Pour drippings and juices from roasting pan into saucepan and set on burner at low heat.
- Stir flour into gravy.
- Adjust with remaining 1/2 cup of water, if needed.
- Just before removing from burner, fold in sour cream and blend well.
Slice tenderloin before serving.
Serve on individual plates with bread dumplings and with individual dollops of sour cream, topped, if desired, with cranberry sauce and lemon slices.