Place the halved tomatoes in an ovenproof dish.
Throw over the garlic and drizzle over half the olive oil.
Roast them for 25-30 minutes at 190°C/375°F/Gas mark 5 until soft and pulpy.
Rub through a sieve to remove the skin and pips.
Heat the remaining oil in a pan and sweat the onion for a few minutes until soft.
Add the beetroot and the stock and bring to the boil. Season lightly with salt and freshly ground black pepper.
Simmer gently for 7-10 minutes until the beetroot is tender.
Stir in the tomato purée, transfer the soup to a blender and process until completely smooth. T
aste and adjust the seasoning if necessary.
Reheat the soup until thoroughly hot but not boiling.
Divide between warm bowls and crumble over a little feta into each bowl. Serve with crusty bread.