Method:

1. Soak the breadcrumbs in the milk for 5 minutes, then combine with the pork mince and onion. Season and use damp hands to roll the mixture into 24 walnut-sized meatballs. Place on a tray, cover and refrigerate for 10-15 minutes.
2. Preheat the oven to 180°C.
3. Heat 2 tablespoons oil in a large ovenproof frypan over medium-high heat. Cook the meatballs in the frypan for 6-8 minutes, turning, until browned. Remove from the pan and set aside.
4. Heat remaining 1 tablespoon oil in the frypan and cook the garlic for 30 seconds, stirring, until fragrant. Add the tomato passata, one whole jalapeño, cinnamon and meatballs to the pan and stir to combine. Transfer to the oven and cook for 15 minutes or until the sauce is bubbling and thickened.
5. Preheat the grill to medium-high. Make a deep slit in the bread rolls lengthways, then toast under the grill for 1 minute or until golden-brown.
6. Tuck some spinach leaves, avocado slices and 6 meatballs into each of the bread rolls. Spoon over a little tomato sauce, then top with gruyere cheese and jalapeño slices. Grill for 1-2 minutes or until the cheese is melted.
7. Serve immediately with fries.