Chef John's Watermelon Pizza

Ingredients

• 1 large seedless watermelon
• 1.5 cups crumbled feta cheese
• 0.5 cup sliced green olives
• 0.5 cup sliced Kalamata olives
• 0.5 cup thinly sliced fresh mint leaves
• 1 pinch freshly ground black pepper to taste
• 2 tablespoons rice vinegar
• 2 tablespoons olive oil