- Preheat your oven To 350 F. 
- Season the pork tenderloin with sea salt and black pepper on both sides. - Sea salt and freshly ground black pepper to taste, 2 lb. pork tenderloin 
- Place the pork in a baking dish. Sprinkle garlic over the pork, top with the onion and celery, and pour the wine and water over everything. - 2 red onions, 1 stalk celery, 4 garlic cloves, 1 cup of red wine, 1 cup of water 
- Bake in the oven for 45 to 50 minutes. 
- When the cooking is done, remove the pork from the dish and add everything else from the baking dish into a saucepan over medium heat. 
- Bring the sauce to a boil. Slowly whisk in the tapioca starch until it thickens, and season to taste with salt and pepper. - 2 tbsp. tapioca starch 
- Slice the tenderloin, pour the sauce over it, and serve.