Preheat oven to 160°C. Place an oven-proof casserole dish over a medium heat. Add the olive oil, red onion and cook until soft. Place the chicken thighs and flour in a bowl and mix until chicken is well coated. Add the chicken to the pot with the onions and cook until the chicken starts to brown. Add the tomato paste and cook for a further minute. Add the tin of chopped tomatoes, Gault's Chicken Stock and bring to a simmer, stirring to ensure any caramelisation is released from the bottom of the pot. Stir in the brown sugar and Simon Gault Home Cuisine Mexican seasoning. Add the chorizo and sweetcorn. Place the lid on the casserole dish and bake in the oven for 45 minutes or until the chicken is cooked right through. Serve with sour cream, crusty bread and a generous sprinkle of coriander.