Peel and cut the watermelon into large cubes. Peel the red onion and cut it into quarters. Remove the centre from each quarter and slice in half again. Cut the feta cheese into cubes. Remove the leaves and chop the flat leaf parsley.
Pour the pomegranate molasses into a bowl and add lemon juice, sumac, salt and pepper. Whisk in the grapeseed oil and then add the olive oil.
Arrange the watermelon cubes, red onion, olives and feta in a salad bowl. Add the vinaigrette and chopped flat leaf parsley and mix thoroughly. Taste and season if necessary. Sprinkle with sumac, pomegranate seeds and dwarf basil and serve.