Mix all the marinade ingredients together. Place the pork in a freezer bag, add the marinade and leave in the fridge for as long as you can – overnight is perfect.
Preheat the oven to Gas Mark 4, 180˚C (350˚F).
To make the pepper sauce: Heat the olive oil in a large frying pan over a medium heat, add the onion, peppers, chilli, garlic, paprika, a little salt, black pepper and sugar. Cook for 10 minutes, stirring occasionally, until the vegetables are softened. Add the chopped tomatoes then pour the mixture into an oven proof baking dish.
Heat a little more oil in the same frying pan. Remove the pork from the marinade, reserve the marinade. Add the pork to the hot pan and seal on all side. Place the pork on top of the peppers. Deglaze the pan with 2 tablespoons of water, add the reserved marinade and simmer for a minute or two. Then pour this over the pork. Cover with foil and place in the pre heated oven and cook for 45 minutes. Remove from the oven and allow to rest for 10 minutes.