Meatballs in Vegetable Sauce

Ingredients (4 servings): 500g lean beef mince 1 green onion, finely chopped 2 tablespoons finely chopped fresh basil 1 egg, lightly beaten 2/3 cup fresh breadcrumbs 2 tablespoons olive oil 2 stalks celery, trimmed, finely chopped 1 medium carrot, grated 1 medium zucchini (baby marrow), grated 500g tomatoes, finely chopped 1/4 cup tomato paste 2…