For the spicy tomato sauce: In a large saucepan, heat the oil over medium heat, then add the onions. Saute until soft and fragrant. Add the garlic and harissa and saute for 2 to 3 minutes. Add the tomatoes and bring to a boil. Stir in the broth and season with salt and pepper. Bring to a simmer, then simmer the sauce for 10 minutes before finishing with the parsley.
For the meatballs: In a large mixing bowl, combine the ground beef, breadcrumbs, onions egg, coriander, cumin, cinnamon, curry powder and dried oregano. Shape the mixture into 35 meatballs.
In a large skillet over medium heat, add 2 tablespoons olive oil. Add half of the meatballs and brown on all sides, 8 to 10 minutes. Remove to a plate and repeat with the remaining olive oil and meatballs. Serve warm with the spicy tomato sauce.
Cook's Notes: Instructions for freezing: After forming and browning the meatballs, place on a parchment-lined baking sheet and put into the freezer overnight. In the morning, remove the sheet tray, place the meatballs in a re-sealable plastic bag and return to the freezer until ready to use.
Instructions for reheating: Preheat your oven to 425 degrees F. Remove the meatballs from the freezer and place on a parchment-lined baking sheet. Bake until the meatballs have cooked through, 10 to 12 minutes.