Half-fill a saucepan with water, then add the whole beetroot and bring the water to the boil. Reduce the heat until the water is simmering, then simmer for 30-45 minutes, or until the beetroot are tender when pierced with the point of a knife. Drain well and set aside to cool.
Put the feta in a dish, squeeze over the lemon juice and scatter over the garlic. Leave to marinate while you prepare the rest of the salad.
Cut the pomegranate in half and pop the seeds out into a bowl by bashing the skin with a spoon.
Toss together the leaves (rocket, spinach and watercress) in a large salad bowl with the olive oil, hemp seed oil, and salt and freshly ground pepper. Crumble in the marinated feta, beetroot and scatter the pomegranate seeds and flaked almonds. Serve immediately.