1. Add half of the onions to a 6-quart slow cooker. Pat brisket dry with a paper towel and season with salt and pepper.
2. Heat oil in a large skillet over medium-high heat until just smoking. Add brisket and cook until golden brown, 3 to 4 minutes per side. Transfer to the slow cooker and top with remaining onions, honey, thyme, and broth.
3. Whisk stout into the hot skillet, scraping up any brown bits, and transfer to the slow cooker. Cover and cook on low until brisket is fork-tender, about 8 hours.
4. Transfer brisket to a cutting board and tent with foil.
5. To make gravy, pour cooking liquid and onions into a large saucepan and simmer over medium-high heat until reduced by about half, 15 to 20 minutes. Stir together water and cornstarch until smooth. Whisk into saucepan and continue to simmer until gravy is thick enough to coat the back of a spoon, 2 to 3 minutes. Skim fat, discard thyme stems, and season with salt and pepper to taste.
6. Slice brisket across the grain, transfer to a platter, and top with about half of the onion gravy. Sprinkle with parsley and serve with remaining gravy on the side.
Source: Hannaford fresh Magazine, March - April 2016