Preheat oven to 425°F. Chop the onion and garlic. Peel the potatoes and cut them into very small cubes. Whisk the egg. Cut the Brussels sprouts in 2 or 4 depending on the size.
2. Cook the meatHeat a drizzle of oil in a large skillet over medium-high heat. Add the potatoes and cook 6-8 minutes. Add salt. Add the veal, onion and tourtière spices. Cook for 4-5 minutes. Add salt and pepper.
3. Garnish the doughRoll the pizza dough with the flour to the desired thickness. Make a large rectangular pizza. Place on a baking sheet lined with baking paper. Top the entire surface of the pizza dough with the veal mixture. For 4 servings, make 2 large pizzas. Roll the dough into a long log. Brush the dough with the whisked egg. Bake in the oven for 18-20 minutes until browned.
4. Cook the Brussel sproutsPlace the Brussels sprouts in a large bowl with the garlic, a drizzle of oil, salt and pepper. Mix then place on a sheet pan covered with baking paper. Bake in the oven for 16-18 minutes.
5. Prepare the ketchupAdd the canned tomato paste, maple syrup, onion powder, a pinch of salt and 1/4 cup of apple cider vinegar in a saucepan. Bring to a boil. Reduce the heat to low and simmer 4-6 minutes until thickened slightly.
6. Plate your dishServe the stromboli with the Brussel sprouts and ketchup. Bon appétit!