Preheat oven to 425F.
Crush coriander seeds in a mortar. Add the fresh herbs and crush together with the coriander seeds.
Mix the crushed herbs and coriander seeds with salt and pepper in a small bowl.
Rub the pork loin with the seasoning, patting it to make sure the seasonings stick well. Position the pork loin on a rack fitted over a baking pan lined with foil. Make sure that the fat cap is on top of the loin.
Insert a BBQ or meat thermometer, put the loin in the oven and roast at 425F for 15 minutes. Reduce temperature to 325F and continue to roast until the temperature in the center of the thickest part of the loin reaches 140F, about 50 - 70 minutes.
Remove the meat from the oven, tent with a piece of foil and let rest for 10 minutes before carving.
Meanwhile, heat the oil in a skillet over medium-high heat. Saute the garlic and the shallot for 1 minute. Add the mushrooms and continue sauteing for another 5 minutes or so, until the mushrooms begin to brown.
Add the sherry wine and continue cooking until most of the liquid evaporates.
Pour in the chicken stock and the soy sauce. Bring to a boil. Add the cornstarch mixture and simmer for about 2 minutes, until it thickens. Season with salt and pepper to taste.
Serve the pork loin with your favorite side dish (these garlic mashed potatoes are the best match for this dish) with mushroom sauce spooned over it.