450g tomatoes
1 jalapeño chile or more to taste, roughly chopped
2 small garlic cloves, roughly chopped
1 tablespoon vegetable oil
125ml water (from the boiled tomatoes)
salt to taste
finely crumbled dried oregano

Cover the tomatoes with hot water in a saucepan and simmer until soft but not falling apart - about 10 minutes.
Drain, saving the hot water.
Put the tomatoes, chile, and garlic into a blender and blend until smooth.
Heat the oil in a small skillet and cook the sauce over high heat for about 2 minutes.
Add the water with salt if necessary and cook for a further 2 minutes.
If using this as a table sauce, sprinkle the oregano on top just before serving.
If using it on food, sprinkle the oregano on top of food.