Melt the butter and olive oil in a medium saucepan over medium high heat. Add the shallot and garlic and cook until soft. Add the rum and reduce to 1/4 cup. Add the stock, bring to a boil and reduce the heat. Whisk in the remaining ingredients and simmer until reduced to 2 cups.
Preheat oven to 450 degrees F. Season tenderloin with salt and pepper on both sides. Place a large ovenproof skillet over high heat, melt the butter and sear tenderloin on all sides. Place in oven and cook to desired doneness or for about 10 to 15 minutes or until a thermometer inserted registers 125 degrees for medium rare.
Wild Mushroom Rice:
Heat 3 tablespoons butter and 2 tablespoons oil in a large saute pan over high heat. Add the mushrooms, season with salt and pepper to taste and saute until golden brown. In a medium saucepan heat remaining oil and butter over medium heat, add the onions and cook until soft. Add the rice and stir to coat with the butter and oil. Add 6 cups of the stock, 1 teaspoon of salt and the porcini powder, bring to a boil, cover, lower the heat and cook until all the liquid is absorbed. Fold in the mushroom mixture, more stock if needed and season with salt and pepper to taste, cook to heat through, 5 minutes.