Heat oil in a large saucepan over medium heat. Add onion and garlic. Cook, stirring for 5 minutes until onion softens. Add tomato paste and cook for 1 minute

Add mince and increase heat to medium-high and cook for 3-4 minutes until browned. Add mushrooms and thyme and cook for a further 3 minutes

Add chopped tomatoes. Bring to the boil and simmer on low for 30-35 minutes until sauce thickens. Season to taste

Spoon 1/2 cup mince onto base of roll. Top with cheese and place under grill for 1 minute until melted slightly. Top with avocado, lettuce and roll tops