Put a large skillet over medium-high heat and add the oil. Season the stew meat with salt and pepper, to taste, and dredge in the flour, shaking off any excess. Add the stew meat to the pan and brown on all sides, about 8 minutes.
Remove the meat from the pan and set aside on a plate. Pour the chicken broth or stock into the skillet to deglaze and scrape up all the brown bits on the bottom. Turn off the heat and let it sit.
To the sleeve of a 5 quart slow cooker add half of the chopped the vegetables and nestle half of the meat on top. Add the remaining vegetables, remaining meat, tomatoes, garlic, the broth from the pan, and the thyme. Season with salt and pepper, to taste. Cover and cook on low for 6 to 8 hours.
About 5 minutes before the stew is ready, make the polenta according to package instructions. Add a pinch of salt and the red pepper flakes to the water before adding the polenta. Once the polenta has thickened remove from heat, stir in the cheese and butter and whisk until smooth.
To serve, put a big spoonful of polenta on each plate. Top with some of the stew and garnish with some fresh thyme leaves, if desired, (Reserve 1 1/2 cups of the stew for round 2 recipe Osso Buco Calzones)