Pre-heat the oven to 190°C ( gas mark 5).
Place the sweetcorn cobs and pepper halves into a baking tray and drizzle with 2 tablespoons of the olive oil.
Place the tray in the pre-heated oven for 25 minutes.
Remove from the oven and set to one side to cool.
When the sweetcorn is cool enough to handle, use a sharp knife to remove the kernels.
Place the remaining 2 tablespoons of olive oil in a large pan over a medium heat.
Add the chopped onions and garlic.
Cook until soft.
Add the sweetcorn kernels and the roasted peppers.
Add chopped oregano.
Add vegetable stock.
Bring to a simmer, then cover with a lid and reduce the heat.
Cook at this lower heat for 20 minutes.
Remove from the heat and leave to cool for at least 15 minutes.
Process the soup in a blender until smooth.