Half the bread and set aside. Add salt and pepper to the vegetables and put them in a pan over medium heat with a little olive oil to brown. When they are golden on both sides, remove them and set them aside.
In a large bowl, put the mixed salad and season well with a little lemon or white wine vinegar, salt and pepper, and a little olive oil. Mix well and set aside
To make the sandwich, put the dijon mustard on one side of the bread in each ciabatta or baguette and a spoonful of pesto on the other. Divide the slices of roasted eggplant, zucchini, and peppers between the four halves. Divide the mixed salad equally and cover the sandwich. Serve immediately.