Here's the original recipe: http://allrecipes.com/recipe/89539/slow-cooker-chicken-tortilla-soup/
You start with a 10 oz. can of red enchilada sauce (here's a place where you can heat the recipe up or down by choosing mild, medium, or hot sauce), a 15 oz. can of tomatoes (I use crushed because I don't like pieces of cooked tomato in my food), and I also add a 15 oz. can of black beans, drained. Add frozen or canned corn, spices (another place where you can heat the recipe up or down; I don't use the cilantro), and chicken. The recipe calls for cooked shredded chicken breast, but I use uncooked boneless skinless breasts. You want about a pound total. They cook in the soup, which gives it a better flavor, then before serving you take them out, shred the meat, and put it back in the crockpot. The recipe also calls for a 14 oz. can of chicken broth and 2 cups of water, but I use 4 cups of chicken broth for a richer flavor. If you want a vegetarian recipe, double up on the corn and black beans, leave out the chicken, and use vegetable broth.
This makes way too much for just the two of us, so what I do is I divide the batch in half (before adding broth) and put half in the slow cooker and the other half in a freezer storage bag and freeze it. Only add the broth when you put it in the crockpot. Also, use two bay leaves, one in the batch you cook now and one in the freezer batch. And tadaa, two dinners for the work of one!
Cooks on low in about 6 hours. I put it together at lunchtime, and it's ready by the time we eat dinner at 6:30.
To serve: the recipe tells you how to make your own tortilla chips, but that kinda negates the point of an easy dinner, so I just use bagged chips from the store. Serve up the soup, crumble tortilla chips into it, and top with shredded cheese, sour cream, lime slices (as per the picture), whatever Mexican food toppings you like. Yummy and easy (and it tastes great the next day!)