To prepare the meatballs combine the ground beef, onion, garlic, tomato puree, salt, pepper and egg together in a large bowl using your hands. Make sure everything is well combined so that the meatballs don't fall apart when cooking.
Form the mixture into 36 one-inch round meatballs and set aside on a plate.
Heat a nonstick frying pan and fry the meatballs in batches until browned on the outside. Transfer to an ovenproof casserole dish.
Meanwhile, combine the brown sugar, vinegar, water, mustard and ketchup in a medium sized saucepan. Whisk over a medium heat until the sugar is dissolved and the mixture starts to bubble.
Thicken the sauce with the cornflour dissolved in a little cold water and pour the sauce over the meatballs.
Transfer the casserole dish to the oven and bake for 30 minutes.
Serve with plenty of rice and a green vegetable on the side.
Food waste prevention tip #1: leftovers freeze well. Simply defrost, place in a casserole dish, cover and bake for 30 minutes to reheat.
Food waste prevention tip #2: batch cook this recipe, making sure the meatballs are cooked through when browning. Freeze for another day.
Mum of three, daydream adventurer, OU Life Sciences graduate, occasional crafter, ex-pat Canadian & quite possibly Britain's most northerly food blogger.