1. Preheat the oven to 325°F (163°C).
2. Season the short ribs generously with salt and pepper, then dust with flour, shaking off any excess.
3. Heat the olive oil in a Dutch oven or other heavy-bottomed pot over medium-high heat. Add the short ribs and brown on all sides, about 2 minutes per side. Remove the short ribs and set aside on a plate.
4. In the same pot, add the onion, celery, carrots, and garlic. Cook until the vegetables are softened, about 5 minutes.
5. Add the rosemary, thyme, bay leaf, and tomato paste. Stir to combine and cook for another minute or two.
6. Pour in the stout beer and beef stock, and stir to combine. Bring the mixture to a simmer.
7. Add the short ribs back to the pot, making sure they are submerged in the liquid.
8. Cover the pot and transfer to the preheated oven. Cook for 3-4 hours, or until the short ribs are tender and falling apart.
9. Remove the pot from the oven and transfer the short ribs to a plate. Discard the herb sprigs and bay leaf.
10. If the sauce is too thin, simmer it on the stovetop until it has reduced to your desired consistency. Stir in the liquid smoke.
11. Serve the short ribs with mashed potato or risotto and spoon the sauce over the top. Garnish with fresh chopped parsley.

Enjoy your delicious Guinness braised short ribs!