Preheat oven to 180 °C (350 °F).

In a small pot, mix vinegar, wine and honey and simmer over medium heat until liquid thickens and reduces by a third.

Remove pot from heat, transfer mixture to a small bowl and season with salt and pepper. Allow to cool to room temperature.

Place slices of bread on a parchment-lined baking sheet. Brush them with 15 mL (1 tbsp.) olive oil and top with cheese. Bake for 5 to 7 minutes or until cheese melts.

Meanwhile, slice tomatoes and place them in a serving dish or divide among four plates, layering them alternately between basil leaves, cheese and red onion slices. Season with salt and pepper. Drizzle with 15 mL (1 tbsp.) olive oil and cooled balsamic reduction. Serve with bread croutons topped with melted cheese.