Whisk together the ingredients for the balsamic glaze.
Heat olive oil a large, oven-safe lidded pot over medium-high heat. Add the onions, whole garlic cloves, and carrots and cook 3-4 minutes per side until browned and remove from the pan.
In a small bowl, combine the salt, pepper, and garlic powder. Season pork roast liberally with the salt and pepper then add to the pan. Brown 5-6 minutes on one side, then flip. Spoon the balsamic glaze over the pork roast, then add the onions and garlic back to the pan, along with the potatoes, mushrooms, broth, and thyme sprigs.
Place the lid on the pot and bake at 325 F for 1 hour, or until the center of the pork roast reaches 145 F.
Remove the roast from oven and let sit for 15 minutes before slicing, then serve!