Pasta with tomato & hidden veg sauce

Name: Pasta with tomato & hidden veg sauce
Prep time: 15 min
Cook time: 50 min
Total time: 1 h 5 min
Cuisine: British
Ingredients: 1 tsp olive oil; 1 large onion chopped; 2 celery sticks, chopped; 2 carrots chopped; 1 leek chopped; 2 peppers deseeded and chopped; 2 cans chopped tomatoes with garlic; 1 tbsp each caster sugar and balsamic vinegar; 300g dried pasta shapes; parmesan shaved, and rocket, to serve (optional)