Caprese Sandwich

Ingredients (12)

• 1 baguette (16 ounces)
• 1 tablespoon thick balsamic vinegar or balsamic glaze*
• 1 tablespoon extra-virgin olive oil
• 1 1/2 cups baby arugula
• 1 mozzarella ball (8 ounces)
• 2 medium ripe tomatoes, sliced into 1/4-inch thick rounds
• Flaky sea salt or kosher salt
• 1 small or 1/2 medium clove garlic, roughly chopped
• 1/2 cup mayonnaise
• 1/2 cup (1 ounce) lightly packed fresh basil
• 1/4 teaspoon fine sea salt
• Lots of freshly ground black pepper, to taste