Heat oven to 200°C, 180°C fan, Gas Mark 6 and grease a large shallow ovenproof dish. Heat the oil in a large pan then add the onion and fry for 10 minutes until it begins to turn golden. Add the passata, vegetable stock and sundried tomato paste and stir well. Stir in the peppers then cover the pan and cook for 10-15 minutes until the peppers are tender. Set aside to cool a little. Remove both ends from the can of beans then carefully push out the contents so it remains in a solid piece. Place on a board and carfully cut into 8 down the length with a sharp knife - do it gently as it is quite soft. Warm the tortillas according to pack instructions. Spoon some of the pepper sauce onto the tortillas and top each one with some beans and a sprinkling of diced cheese. Roll up and place in the dish. Spoon over the crème fraîche to cover then scatter with the grated cheese. Bake for 25 minutes until golden and bubbling. Serve with a salad, and rice if you like.