While lid to clay baker is soaking (soak top & bottom for unglazed bakers), remove excess fat from tenderloin and cut into bite-size cubes (about 1"). Place pork cubes, vegetables, and bay leaf in clay cooker base. Mix together flour, dried thyme, dried rosemary, and salt and pepper. Sprinkle over pork and vegetables and stir to distribute evenly. Let sit for 2-3 minutes to let flour and seasonings absorb into pork. Mix together chicken broth, vinegar, and sugar. Pour over pork and vegetables. With cooking twine, tie together fresh herbs and place on top of pork mixture. Place lid on baker, place in oven and set oven temperature to 450 degrees Fahrenheit. Bake 1 to 1 1/2 hours or until pork is tender and mixture is bubbling.
Meanwhile, stir together cornstarch and heavy cream (or half and half). Let sit at room temperature while stew cooks.
Remove baker from oven when pork is tender, carefully remove the lid and quickly stir in cornstarch mixture. Stir for about 1 minute to thicken the stew. Remove bay leaf and fresh herb bundle (if using). Stir in sour cream and garnish with chopped flat-leaf parsley if desired.
This recipe is easily halved.