Heat the olive oil in a large Dutch oven over medium-high heat.
Season the beef cubes with salt and pepper. In batches, brown the beef on all sides, about 5-6 minutes per batch. Remove the beef and set aside.
In the same pot, add the sliced onions and cook until they are softened and caramelized, about 10 minutes. Add minced garlic and cook for another minute.
Sprinkle the flour over the onions and stir to combine, cooking for 1-2 minutes.
Stir in the tomato paste and cook for another minute.
Add the browned beef back to the pot, followed by the beef broth and Belgian beer. Stir well to combine.
Add the brown sugar, thyme, bay leaf, and additional salt and pepper to taste. Bring the mixture to a simmer.
Cover the pot and reduce heat to low. Let the stew simmer for about 1.5 hours, stirring occasionally, until the beef is tender.
If the stew is too thick, add a little more broth or water. Remove the bay leaf before serving.
Serve the stew hot, garnished with chopped fresh parsley.