To make the meatballs, put the onion, garlic, haloumi, oregano, parsley, parmesan cheese and egg in a large bowl and mix well. Break up the mince, add to the bowl with salt and pepper to taste, and mix until well combined. Roll the mixture into 3–4 cm (1½ -1 3/4 inch) round balls and refrigerate for 30 minutes or more.
Heat the olive oil in a medium saucepan over medium heat. Add the meatballs and cook, moving them around frequently, for 5 minutes, or until golden brown. Transfer to a bowl. To make the smoky tomato sauce, using the same saucepan, cook the onion, garlic, capsicum, chilli, celery and fennel seeds for 7 minutes, until tender. Add the paprika and tomato paste and cook for 2 minutes.
Reduce the heat to low, add the tomato and cook for 10 minutes to develop the flavours and reduce the sauce. Add the meatballs to the sauce and simmer for 5 minutes, or until tender and cooked through. Transfer the meatballs and sauce to a serving bowl. Scatter over the extra parsley, and serve with lemon wedges and sourdough.