Heat oven to 480 (250C) and line a baking tray with parchment paper. Cut your red bell peppers in half lengthways and remove the stem, pith and seed with your hands. Lace them cut side down on the tray and spray with cooking spray.
Cook in oven for around 25 minutes or until the skin of the peppers is blistered and slightly blackened.
Transfer to a bowl and cover with plastic warp for around 1 hour.
Remove the plastic warp and gently peel off the skin from the flesh of the peppers.