Sift the flour, baking powder and some salt into a bowl. Make a well in the centre.
In a jug, beat together the egg and milk and pour into the flour. Whisk until you have a reasonably thick batter (you may not need to use all the milk).
Put the sweetcorn in another bowl and add the batter.
You may not need to use all the batter - you are aiming for quite a thick sweetcorn mixture.
Heat the oil in a frying pan over a medium heat and, when hot, spoon in tablespoons of the batter.
Fry for a few minutes on each side. Keep warm while you make the salsa.
Heat the oil in a frying pan, add the onion and cook over a medium heat until soft.
Add the chorizo and the garlic, and, once the chorizo has a nice bit of colour, add the tomatoes and the pureé.
Season and cook until the tomatoes have softened and the sauce is coming together, but still chunky.
Stir in the sugar and cook for a further minute. Stir through the coriander.
Serve the salsa warm, on top of the fritters, with a dollop of soured cream and an extra sprinkle of coriander.