Instructions:
- Prepare the Watermelon Base: Trim both ends of the watermelon. Stand it upright and carefully slice off the rind, working from top to bottom. Cut the remaining flesh into four thick, round discs (about 1-inch / 2.5 cm thick). Trim any remaining white pith. Place discs on a platter and brush lightly with lime juice. Chill for 10 minutes.
- Make the Balsamic Glaze (Optional): Combine vinegar in a small saucepan. Bring to a gentle simmer over medium heat. Reduce heat to low and let it bubble gently until the volume is reduced by half and coats the back of a spoon (about 5-7 minutes). Cool completely.
- Whip the Feta: Combine feta, softened cream cheese, olive oil, and lemon zest in a food processor. Pulse until completely smooth, creamy, and light.
- Toast the Nuts: Place pine nuts in a dry skillet over medium heat. Toss frequently until fragrant and lightly golden brown. Set aside to cool.
- Assemble the Pizzas: Remove chilled watermelon slices. Spread a generous, even layer of the whipped feta mixture over each slice, leaving a small border around the edge.
- Garnish: Sprinkle evenly with chopped fresh mint and toasted pine nuts. Finish with a few cracks of black pepper.
- Drizzle and Serve: Just before serving, use a spoon to drizzle the cooled balsamic glaze artfully over the top of the 'pizzas'. Serve immediately.