1Boil tomatoes for about 6 minutes until they are soft.
2Toast the guajillo chile, remove the seeds, and soak it in boiling water for about 10 minutes.
3In a blender, combine the boiled tomatoes, a quarter of an onion, two cloves of garlic, a big pinch of salt, a package of Mexican oregano, and the soaked guajillo chile.
4Blend until smooth.
5Cook the sauce in a hot skillet with a little bit of oil until it thickens.
6In a bowl, mix the masa and water until a ball is formed.
7Flatten the masa, add beans and cheese, and close the pupusa.