Slice the chorizo, then put these in a heated pan. Fry at a low temperature to release the fat.
Slice the leek and pepper, then add to the Chorizo. Sauté under cover for 5 minutes, then add the chicken and tomatoes to warm through.
Beat the eggs lightly in a bowl, season with salt and pepper. When the tomatoes start releasing their juices and the vegetables are soft, pour over the eggs. Cover, then simmer over very low heat.
When the top of the eggs is wobbly but no longer runny, turn it over (like a pancake) or brown the top under the grill in your oven.
Slide it onto a plate. Sprinkle with basil leaves just before serving.