In a large saucepan heat oil over medium high heat on stove top. Add onion, bell peppers and garlic and cook for 5-6 minutes stirring constantly. Add zucchini and mushroom and cook for a further 10 minutes.
Slowly add white wine and cook for a further 5- 10 minutes till reduced. Add tins of tomatoes, rosemary, sugar and season. Stir well to combine and taste to check seasoning.
Cook for a further 35-40 minutes or until liquid is reduced. Stirring every 10 minutes or so. Eat immediately or let it cool before placing in fridge.