Step 1: Prepare the Short Ribs. Start by taking 3-4 lbs of bone-in beef short ribs out of the refrigerator and letting them come to room temperature for about 30 minutes. Pat the ribs dry with paper towels, then generously season all sides with kosher salt and freshly cracked black pepper to enhance the flavor of these Slow-Braised Beef Short Ribs.

Step 2: Sear the Ribs. In a large Dutch oven, heat 2 tablespoons of olive oil over medium-high heat. Once the oil is shimmering, sear the seasoned short ribs, turning occasionally, until they are deeply browned on all sides, which should take about 8-10 minutes. Remove the ribs from the pot and set them aside on a plate while keeping the drippings in the pot for the next steps.

Step 3: Sauté Aromatics. In the same pot, add 1 large finely chopped yellow onion and sauté over medium heat until softened, approximately 5 minutes. Stir in 4 minced garlic cloves and cook for an additional minute, followed by 2 tablespoons of tomato paste. Cook until fragrant and caramelized, about 2 minutes, which will add depth to your Slow-Braised Beef Short Ribs' flavor.

Step 4: Deglaze the Pot. Pour in 1 cup of dry red wine to deglaze the pot, scraping up all the flavorful browned bits from the bottom with a wooden spoon. Allow the wine to simmer for 3-4 minutes, reducing slightly, which will enhance the sauce and enrich the braising liquid for your short ribs.

Step 5: Add the Braising Ingredients. Once the wine has reduced, add 2 cups of beef broth, along with 2 sprigs of fresh thyme, 2 sprigs of fresh rosemary, and 2 bay leaves. Return the seared ribs to the pot, positioning them to be partially submerged in the aromatic liquid, which will ensure even flavor throughout the braising process.

Step 6: Braise the Ribs. Cover the Dutch oven and transfer it to a preheated oven set to 325°F (160°C). Allow the ribs to braise for 2.5 to 3 hours, or until they are fork-tender and the meat is falling off the bone. Check for doneness occasionally, as oven temperatures may vary, ensuring that your Slow-Braised Beef Short Ribs are perfectly cooked.

Step 7: Prepare the Mashed Potatoes. While the ribs are braising, bring a large pot of salted water to a boil and add 2 lbs of peeled and chopped Yukon gold potatoes. Cook until the potatoes are tender, around 15-20 minutes. Drain well, then mash the potatoes with 4 tablespoons of unsalted butter, ½ cup of heavy cream or milk, and season with salt to taste for a creamy side dish.

Step 8: Make the Creamy Herb Sauce. Once the ribs are cooked, carefully remove them from the Dutch oven and set aside. Strain the braising liquid through a fine sieve into a bowl. In a saucepan, melt 1 tablespoon of butter over medium heat and sauté 2 minced garlic cloves until fragrant. Sprinkle in 1 tablespoon of all-purpose flour and cook for 1-2 minutes to create a roux for your creamy sauce.

Step 9: Combine for the Sauce. Gradually whisk in 1½ cups of the strained braising liquid along with 1 cup of heavy cream, bringing the mixture to a simmer. Continue cooking until the sauce thickens, stirring occasionally, and then stir in 1 teaspoon of Dijon mustard, 2 teaspoons of chopped fresh sage, and 1 teaspoon of fresh thyme leaves. Adjust the seasoning with salt to enhance the flavors.

Step 10: Serve and Enjoy. To serve your delightful Slow-Braised Beef Short Ribs, place a generous spoonful of the creamy herb sauce over the ribs atop a bed of fluffy mashed potatoes. For an extra touch, garnish with fresh herbs. This comforting dish will surely become a family favorite at your dinner table!