Microwave chilies for 20 seconds and remove stems and seeds. Or heat them in a skillet on medium heat until pliable.
Heat a small frying pan on high heat. When it's hot, add the onion, tomatoes, and garlic and char, turning occasionally to get all the sides.
Place the chilies, onion, tomatoes, garlic, oregano, and marjoram in a medium saucepan and fill with water until everything is slightly covered.
Bring to a boil and then reduce heat, letting it simmer for 15 minutes.
Pour everything into a blender. If you want a little more spice, add the whole chilies in adobo + sauce. Blend on high speed until smooth.
Heat a tablespoon of oil in a frying pan. Once it's hot, pour the enchilada sauce into the hot pan (this can be a little scary and it splatter pretty bad).
Reduce heat to medium low and simmer for 30 minutes until the sauce has thickened. Add salt to taste.