Healthy Pan Bagnat Grilled Cheese

Ingredients

• 2 tablespoons sherry vinegar
• 2 teaspoons freshly squeezed lemon juice
• 7 teaspoons olive oil, divided
• 1⁄4 teaspoon freshly ground black pepper
• 2 cans (each 7 oz) solid white tuna, packed in water, drained
• 1 tablespoon finely chopped red onion
• 1 tablespoon chopped fresh basil
• 8 slices sprouted or whole-grain (1⁄2-inch thick slices)
• 4 roma (plum) tomatoes, thinly sliced
• 1 cup baby spinach leaves
• 4 ounces shaved parmesan cheese