Chop the tomatoes, onions, and bell peppers, and peel the garlic. Sprinkle the tablespoon of oil onto the vegetables. Pre-heat grill to 200* centigrade and grill vegetables for 15 minutes.
Remove vegetables from grill and add to a blender or food processor. Add your spices and pulse until finely blended.
Transfer to a pan and cook on low to medium heat stirring frequently to avoid burning. Add the stock cube and let simmer for a further 15 minutes.
Your pepper sauce can be stored for up to a week in the fridge.