Place the tomatoes in a grill pan and cook under a preheated hot grill for 5 minutes until starting to char. Turn the tomatoes over, then add the chillies and cook for a further 5–10 minutes, turning frequently, until they are softened and charred. Leave to cool slightly, then transfer to a food processor or blender, add the garlic and measurement water and whizz to a chunky sauce. Season well and add the dried oregano.
Heat the oil in a small frying pan, add the chorizo and cook for 2 minutes, stirring frequently. Add the tomato sauce and cook for 5 minutes until slightly thickened. Divide the sauce among 4 individual ramekins, then crack an egg into each one.
Place the ramekins on a baking sheet and bake in a preheated oven, 200°C (400°F), Gas Mark 6, for 12 minutes, or until the eggs are just set. Serve with corn tortillas.