Tortilla soup brightens a gray day

The weather here in St. Louis has caught up to the calendar. The day is gray, wet and chilly -- and I know I'm not the only one thinking longingly of soup.
Both the temperature and the spiciness in tortilla soup will warm you up. Once you add the crunch of tortilla chips, the creaminess of avocado and the satisfying shreds of chicken, this bowl of soup contains just about everything you could want in a winter meal.
This recipe isn't strictly authentic, but I think you'll like it anyway. I've made it for years and have never seen a bowl that wasn't scraped clean. Most tortilla soups are thickened with pieces of corn tortillas that dissolve as the soup simmers. I stray from conventional recipes by using grits. It's a technique born of necessity, when I was out of tortillas but craving tortilla soup. Trial and error taught me to grind the grits in a clean coffee grinder; otherwise, the tiny grains don't dissolve. You can substitute corn flour (which won't need to be ground) or cornmeal. Just stay away from self-rising cornmeal, which has salt and leavening that don't belong in a pot of soup.
This recipe also is a great way to use leftover baked or roasted chicken. Supermarket rotisserie chickens practically were made for tortilla soup, especially if you buy one of the giant club-store varieties that are too, too big for most families to eat in one meal.
Canned chipotles used to be sold whole in adobo sauce and needed to be pureed by the cook. Now, however, you can buy small cans of pureed chipotles (which are smoked jalapeno chiles, by the way). You'll have most of the can leftover. Pour the excess into a quart-size zip-top freezer bag, spread into a thin layer, and freeze flat. Next time you need some puree, take it out of the freezer and break off the amount you need.

TORTILLA SOUP
Yield: About 6 servings

1 teaspoon olive oil
1 large onion, chopped
2 cloves garlic, minced
1 (14 1/2-ounce) can diced tomatoes
1 (14 1/2-ounce) can fire-roasted diced tomatoes
32 ounces low-sodium chicken broth
1 tablespoon dry corn grits or cornmeal, ground to a powder, or 2 teaspoons corn flour 
1 to 1 1/2 teaspoons Southwestern-style salt-free seasoning blend or to taste
1 teaspoon chipotle puree or to taste
1 cup fresh or frozen corn kernels
1 tablespoon chopped fresh cilantro, plus cilantro sprigs for garnish
1 1/2 cups shredded cooked chicken 
About 1/2 cup shredded Cheddar cheese or Mexican-style cheese blend
Tortilla chips, for garnish
1/2 avocado, cut into chunks
1 lime, cut into wedges

Heat oil over medium-high heat in a large pot. Add onion and garlic; cook, stirring frequently, until onion begins to brown. Add both cans of tomatoes and broth. Bring to a simmer, then stir in ground grits. Stir in Southwestern seasoning and chipotle puree. Let simmer about 30 minutes, stirring occasionally.

Stir in corn; when corn is cooked, remove soup from heat. Stir in chopped cilantro.

Place 1/4 cup chicken in each soup bowl. Ladle soup over chicken. Top each serving with a heaping tablespoon of cheese, tortilla chips to taste, a few avocado chunks, a lime wedge and a sprig of cilantro. Before eating, squeeze lime into the soup.