Preheat oven to 400F. Grind fennel and caraway seeds into a powder by placing them into a coffee grinder or food processor. Place the mixture on a plate. Season the loin with salt and pepper to taste and dredge on all sides with the spice mixture. Heat the oil in a medium skillet over high heat until almost smoking. Sear the lamb loin on all sides until golden brown. Transfer the lamb to the oven and roast for 8 to 10 minutes for medium-rare doneness. Remove and let rest. Place the skillet on top of the stove over high heat. Remove all but 2 tablespoons of the fat. Add the shallots and cook until soft. Add the wine and cook until reduced by 3/4. Add the chicken stock and cook until reduced by half. Whisk in the mustards and season with salt and pepper to taste. Remove from the heat and stir in the mint. Yields 4 servings.