First chop, season (except chilli flakes and 2tsp of oregano) and roast the tomatoes at gas mark 6 for 45 minutes. Or how ever well done you prefer them (my oven is a bit brutal sometimes

Meanwhile slice and fry the onions in the chilli flakes and remaining oregano until golden

When the tomatoes are done mix them with the onion in a big pot and add the stock powder and a tablespoon of of water

Once mixed transfer to a blender. Blend together then blend in the butter and yoghurt

Rerun to the pan to heat up or save for later and heat again