DO-AHEAD TIP: Bring sour cream to room temperature (see recipe).
Season pork chops with salt, pepper and garlic powder; dredge in 1/2 cup of the flour.
Coat a large skillet with olive oil over medium-high heat; add pork chops and lightly brown on both sides; transfer to a slow cooker and top with onion slices.
Pour broth over the onion and pork chops.
Cover and cook on LOW for 6 to 7 hours.
With a slotted spoon, CAREFULLY remove the very tender pork chops from the slow cooker; keep warm.
In a small bowl, blend remaining 2 tablespoons of flour with the sour cream; stir into slow cooker juices.
Raise slow cooker heat setting to HIGH and cook for 15 to 30 minutes or until sauce has slightly thickened. Serve sauce over pork chops.