For the Poolish: In the bowl of a stand mixer fitted with a paddle attachment, combine flour, sourdough starter, and 278 grams water. Wrap bowl tightly in plastic wrap and let sit 12 hours at room temperature.

For the Dough: In the bowl with the Poolish, add cane syrup, yeast, flour, and 285 grams water. Using the dough hook attachment, mix 5 minutes on medium speed. Let sit 30 minutes at room temperature. Add salt and continue to mix 10 minutes on medium-high speed, or until dough is smooth and elastic. Transfer to an oiled mixing bowl. Wrap bowl tightly in plastic wrap and refrigerate 24 hours.

For the Caramelized Onion Filling: In a saucepan over low flame, heat oil. Add garlic and cook 30 minutes, or until tender. Using a slotted spoon, remove garlic and transfer to a small mixing bowl. Using the back of a spoon, smash garlic. Set aside. Transfer garlic oil to a skillet. Add onions and salt. Place skillet over medium-low heat and cook until onions are soft and translucent, stirring frequently. Add 1 tablespoon water if needed to soften and prevent browning. Remove from heat and stir in garlic. Let cool. Once cooled, transfer to an airtight container and refrigerate.

For the Breakfast Sausage: Place pork in a large mixing bowl. Set aside. In a separate bowl, combine all seasonings and a pinch of nutmeg. Sprinkle mixture over pork. Set aside. In a small mixing bowl, whisk together syrup and 2 tablespoons water. Pour syrup mixture over pork. Using gloved hands, combine mixture until pork is evenly coated. Be careful not to overmix. Wrap bowl tightly in plastic wrap and refrigerate 1 hour. Once chilled, divide pork mixture into ⅓-cup portions. Roll into balls. Wrap tightly in plastic wrap and refrigerate.

For the Burger Sauce: In a mixing bowl, whisk to combine all ingredients. Transfer to an airtight container and refrigerate.

For the Bialys: On a floured work surface, divide Dough into 125-gram portions and roll into balls. Let rest 15 minutes. Using your thumbs, press into the center of each Dough ball, continuing to press outwards until a 1-inch round edge is formed. Stretch the inner edge until the center divot is approximately 5-inches by 3-inches in size. The center should be as thin as possible without tearing. Transfer 6 Dough rounds to floured, parchment-lined 13-inch by 18-inch baking sheet. Fill divot with 1 heaping spoonful Caramelized Onion Filling. Using the back of a spoon press Caramelized Onion Filling down until even with the raised edge. Top with poppy seeds. Let proof 2 hours at room temperature. Heat oven to 475°F. Bake filled Dough rounds 14 minutes, rotating halfway through. Let cool.

For the Breakfast Smashburger: Heat a large non-stick skillet over high heat. Once hot, add 2 portions Breakfast Sausage. Top each with layer of shaved onion. Season with salt and pepper. Using a flat spatula, smash Breakfast Sausage down until desired thickness. Cook 2 minutes, or until edges are no longer pink and begin to crisp. Flip patties and place 1 slice cheese on each Breakfast Sausage. Cook until onions are caramelized and pork is cooked through. Remove from heat. Top 1 patty with fried egg.

To Assemble and Serve: Slice and toast 1 Bialy. Place top half onto Breakfast Smashburger with the fried egg and press down. Using a spatula, carefully lift and place on top of remaining Breakfast Smashburger. Set aside. On a serving plate, place bottom half Bialy. Spread with desired amount Burger Sauce. Top with stacked Breakfast Smashburger and serve.