Start by rehydrating the dried mushrooms in the Imperial Stout, letting both sit in a small bath for 20 – 30 minutes. In a skillet or Dutch oven, over medium-high heat, add the oil and brown off the cubed beef, seasoning lightly with salt. Once browned on all sides, remove with a slotted spoon to a bowl and let sit. Next, add the sliced onions and bay leaves, seasoning lightly with salt and dropping the heat to medium. Slowly caramelize the onions to a dark brown color, about 12 minutes. When the onions begin to turn golden brown, add in the chopped roasted garlic and the cooked meat. Dice the mushrooms, add the fungus with the Imperial Stout to the pot, and turn down the heat to cook on low, until the mixture forms a stew-like consistency. This will take about 30 minutes on the stove, stirring occasionally. Or set in the oven at 325°F | 163°C covered with a tight-fitting lid for an hour. The finished filling will be still moist, but more of a gravy consistency. Chill the filling down to room temperature, then place into a container and refrigerate until cold. This mixture can be made in advance and will get better the second day, like a good stew.