Heat oven to 220C/200C fan/gas 7. Make the meatballs by mixing together the minced beef, breadcrumbs, 3 tbsp of the black bean sauce, 1 tbsp each of sweet chilli sauce and ketchup, and 1 tsp five-spice. Shape into walnut-sized meatballs. It will be quite wet, but this is fine – just oil your hands first and roll gently. Transfer to a baking tray in a single layer and cook for 25 mins, turning once, until golden brown.
Meanwhile, cook the noodles following pack instructions, drain and set aside. Heat the oil in a wok or large frying pan. Cook the vegetables for a few mins, then add the noodles and remaining black bean, sweet chilli, ketchup, five-spice and the soy sauce, tossing well to coat everything.
Serve divided between 4 bowls, topped with the meatballs and sprinkled with the sesame seeds and mint.