Preheat your grill. Brush olive oil on both sides of the watermelon and sprinkle with a bit of salt.
Put the watermelon slice on the grill and cook for 2 to 3 minutes, until you get grill marks. Then flip to the other side and cook another 2 minutes. Transfer to a serving plate.
Topping ingredients are approximate measures depending on the diameter of your slice. Spread the ricotta in a an even layer on the watermelon slice and top with the blueberries, cherries, strawberries.
Drizzle with chocolate syrup and top with mint. Cut into 6 to 8 wedges and serve immediately.