You can get both Spanish and Mexican varieties of chorizo, for this recipe I used Spanish, though it will work well with Mexican as well. Spanish chorizo is seasoned with garlic and paprika, so it has more of a smokey flavor, where as the Mexican varieties are flavored with vinegar. The main difference between these two varieties is that you can not slice the Mexican chorizo like you do the Spanish, it has more of a ground beef texture, so the finished dish will look slightly different. You can use a milder chorizo if you are more sensitive to spicy foods. If you can't get chorizo, Andouille sausage or Kielbasa make good substitutions.