First you need to take the chiles and remove the seeds. I break them up, as much as necessary to remove the seeds and the stem area. You should also remove most of the veins if not all. When each one is accomplished, throw it into a pot that can accommodate them and the water. When they are all seeded etc. put it on the stove with the water and turn it on to a low heat. Now add the coarsely chopped onion and garlic along with your tomatoes, also coarsely chopped. You are trying to soften chiles but they should also smell good too. This process should take about 5 minutes.
When the chiles are softened, you need to in batches put it in your blender and add the cumin, celery salt, beef broth powder and Mexican oregano.
A lot of this is done by taste again, after it is cooking again.
From the blender you will pour it into a wire sieve over a bowl or pot that can handle the amount you are doing. Do this in batches as well. Use a spoon and keep pushing the juice through, till all you have left in there is the pulp. I keep a trash can right there by me for this. I then take the sieve and empty it in the trash.
When all of your sauce is done, pour it into your pan again and cook it at a low heat to blend the spices in. Here is where your taste test comes in and you check the consistency of your sauce.
If it is too thick, you can add some water. If it is too thin, you can add some tomato puree, some tomato paste, or you can do a flour mixture as if you were making gravy. You can always add some chili powder and more cumin and celery salt if it is too mild. The tomato sauce or puree will help also if it is too hot. (*I always use celery salt when using cumin, as cumin seems to suck out the salt, so if you use the cumin always add the celery salt.*)
YOUR SAUCE IS NOW READY FOR USE!