Heat a frying pan over medium heat. Add in the oil and the onion. Sauté until onion has softened and sprinkle the sugar evenly over the onion. Sauté until the onion is browned and lightly caramelised. Remove from heat and let cool completely.
Place bread crumbs in a bowl and pour in 1/8 cup of water. If the bread crumbs are still dry, add remaining water bit by bit until moisten. Discard unused water. Soak the bread crumbs for 15 minutes.
In a large mixing bowl, combine the minced meat, caramelised onion, soaked bread crumbs, herbs, cheese, egg, ketchup, paprika, salt and plenty of freshly ground black pepper. Mix the mixture very well (I used my hand).
*At this point you can scoop a small spoonful of mixture, pan-fry and taste it. Adjust the seasoning and test again until you are satisfied.
Line a baking sheet with parchment paper. Scoop a small spoonful of mixture and roll into a ball, about 1 inch in diameter (check the meatballs once in a while to ensure they are relatively of the same size). Set the meatballs on the lined baking sheet. Freeze the meatballs for at least 1 hour before cooking.
*Meatballs can be made ahead until this point. Freeze meatballs for at least 4 hours. Transfer them into a ziploc bag to store in the freezer.
Oven-bake: Preheat oven to 190 degrees Celsius. Drizzle the meatballs very lightly with oil and bake for 15 minutes. Flip the meatballs and bake for another 10 minutes until the meatballs are browned on both sides and cooked through.
Pan-fry then bake: Preheat oven to 190 degrees Celsius. Heat a frying pan until hot and drizzle in a little oil. Add in the meatballs in a single layer and sear both sides until browned. Bake the meatballs for another 10 to 15 minutes until cooked through.
Serve the meatballs plain, with pastas, with mushroom sauce or simply with ketchup.