01 - In a large skillet over medium-high heat, heat olive oil. Brown beef cubes in batches, approximately 3–4 minutes per batch. Transfer browned beef to the slow cooker.
02 - Add the diced onion, minced garlic, sliced carrots, sliced celery, and diced potatoes to the slow cooker with the beef.
03 - In a separate bowl, whisk together the beef broth, red wine (or additional broth), tomato paste, and Worcestershire sauce. Pour this mixture over the beef and vegetables in the slow cooker.
04 - Incorporate the fresh thyme, chopped rosemary, bay leaves, salt, and black pepper into the slow cooker. Stir gently to combine all ingredients.
05 - Cover the slow cooker and cook on LOW for 7 hours or on HIGH for 4 hours, until the beef and vegetables are fork-tender.
06 - Thirty minutes prior to serving, remove and discard the bay leaves. Stir in the cornstarch slurry to thicken the stew to your desired consistency.
07 - While the stew is thickening, prepare the dumplings. In a mixing bowl, combine the all-purpose flour, baking powder, baking soda, and salt. Cut in the cold unsalted butter using a pastry blender or your fingertips until the mixture resembles coarse crumbs. Stir in the finely chopped dill pickles, chopped fresh dill, and chopped fresh parsley. Gradually add the buttermilk, mixing just until a cohesive batter forms; avoid overmixing.
08 - Drop tablespoonfuls of the dumpling batter directly onto the surface of the hot stew. Cover the slow cooker and continue cooking on HIGH for 30 minutes, or until the dumplings are fully puffed and cooked through.
09 - Serve the beef stew hot, garnished with additional fresh dill or parsley, if desired.