Sandwiches with grilled vegetables and fresh mozzarella - Au Pain Doré

Ingredients

• 4 beet and onion breads
• 1 red onion, thinly sliced
• 3 half peppers of various colors, thinly sliced
• 1 small zucchini, sliced
• 30 ml (2 tablespoons) of olive oil
• 5 ml (1 teaspoon) of dried Italian herbs
• Salt and pepper, to taste
• 250 g (about 1/2 lb) of sliced fresh mozzarella
• 310 ml (1 1/4 cups) of baby spinach
• For the flavored mayonnaise: 160 ml (2/3 cup) of mayonnaise 30 ml (2 tablespoons) of freshly minced basil 15 ml (1 tablespoon) of whole grain mustard 10 ml (2 teaspoons) of honey