For the Red Wine Braised Short Ribs:

1. Preheat the oven to 325°F.
2. Pat short ribs very dry with paper towels and season all over with salt.
3. Heat a Dutch oven over medium high heat, and once hot, drizzle in the olive oil. Working in batches to avoid overcrowding the pot, sear the short ribs for 3-4 minutes per side, or until deeply browned all over. Transfer to a plate and repeat with the remaining short ribs, draining some of the excess fat between batches as needed.
4. Once all short ribs have been seared on all sides, carefully pour off all but about 2 tbsp of fat from the Dutch oven. Reduce the heat to medium, and add the garlic head, cut side down. Add the shallots, carrots and celery, and salt and pepper. Cook vegetables for 5–7 minutes, stirring occasionally, until softened and beginning to caramelize.
5. Add the tomato paste and mushroom umami seasoning, and cook for 1-2 minutes, stirring frequently, until the tomato paste darkens slightly and begins to stick to the bottom of the pot.
6. Pour in the entire bottle of red wine, using a wooden spoon to scrape up all of the browned bits from the bottom of the pot. Bring to a simmer and cook uncovered for 12–15 minutes, or until the wine has reduced by about half.
7. Nestle the short ribs back into the Dutch oven along with any resting juices. Add in the chicken stock, rosemary, thyme, and sage. The liquid should come most of the way up the sides of the ribs without completely covering them. Add additional stock as needed.
8. Bring the liquid to a simmer, then cover the Dutch oven and transfer to the oven. Braise for 3–3½ hours, or until the short ribs are very tender and easily pull apart with a fork.
9. Carefully transfer the short ribs to a plate or serving dish. Remove and discard the herb stems. Remove the garlic head, squeeze the softened cloves back into the braising liquid and stir to combine. Strain the braising liquid through a fine mesh strainer, pressing the juices out of the vegetables. 
10. For the best results, let the short ribs and sauce cool and refrigerate overnight. The rendered fat will rise to the surface and harden, allowing you to easily lift it off the next day. If serving the short ribs the same day, pour the braising liquid into a tall, heat-safe container, let it cool slightly, then freeze for 15–20 minutes, or until the fat rises to the surface and begins to solidify. Skim off and discard as much fat as possible.
11. Pour the braising liquid back into the Dutch oven and bring to a gentle simmer. If you’d like a thicker, more concentrated sauce, simmer uncovered for 10–15 minutes, or until reduced to your desired consistency. Taste and adjust with salt and pepper as needed.
12. Return the short ribs to the sauce and spoon the sauce over the top. Cover and gently heat until the ribs are warmed through. Serve over creamy mashed potatoes with plenty of the sauce spooned over.