Cook the baguette, following the pack instructions. Allow to cool before slicing in half lengthways.
Place the courgette and aubergine onto a baking tray and lightly coat with spray oil. Cook under a medium grill for about 10 minutes, turning halfway through until soft and lightly browned.
While the courgette and aubergine cook, coat a frying pan with spray oil and warm over a medium heat. Add the pepper with a splash of water (to prevent sticking) and cook, stirring regularly. When the pepper starts to soften, after about 5 minutes, add the onion and cook for a further 5 minutes. Add more water as is necessary.
Lightly toast the cut sides of the baguette under the grill. While still warm, coat one side with a thin layer of plant-based spread. Add the cooked vegetables and enjoy warm!