The ingredients for one authentic Mexican salsa recipe are 14 ounces of stewed tomatoes, 8 to 20 dried arbol chilis, 1/2 of a small onion, 1 sliced jalapeño pepper, 1 garlic clove and fresh cilantro. Puree the ingredients in a blender, adding 1 teaspoon of lime juice, salt and pepper.
To begin, remove the stems from the dried arbol chilis. Use fewer chilis for milder salsa, and use the maximum amount for very hot salsa. Place the dried chilis and seeds in the blender, and blend them thoroughly. Add the stewed tomatoes with juice. Add the remaining ingredients, and season the mixture to taste. Puree the salsa in the blender until it reaches a desired consistency. Use lemon or lime juice for this recipe.
Another recipe for authentic Mexican salsa uses fresh ingredients. Husk and rinse 5 to 6 medium tomatillos. Remove the stems from 1 fresh jalapeño pepper or 2 fresh serrano peppers. Coarsely chop the fresh peppers and tomatillos, and place them in a blender or food processor. Process the mixture, along with 1/4 cup of water and 5 to 6 sprigs of chopped cilantro, until it is coarse. Place the mixture in a serving bowl. Rinse 1/4 cup of finely chopped onion under water, and drain it until the excess water is removed. Stir the onion into the blended mixture, and season it with about 1/4 teaspoon of salt.