Ingredients

• 1/2 cup mayonnaise
• 2 teaspoons Dijon mustard
• 1 teaspoon fresh lemon juice
• Kosher salt
• 1 large shallot, thinly sliced into rings
• 1 garlic clove, finely grated
• 3 tablespoons red wine vinegar
• 1/2 baguette, split in half lengthwise
• 4 tablespoons olive oil, divided
• 3 cups cherry tomatoes
• Freshly ground black pepper
• 1 cup (packed) torn basil leaves
• 1/2 cup (loosely packed) parsley leaves with tender stems
• 1/2 teaspoon finely grated lemon zest
• 4 ounces fresh mozzarella, torn into pieces
• Crushed red pepper flakes (for serving)