In a cast iron pan or heavy bottom pot, heat the oil over medium-high heat. Add 1/4 of the tortilla strips and cook, stirring, until pale golden, about 1-2 minutes. Stir once or twice with tongs or slotted spoon while cooking to avoid sticking. Remove and drain on paper towel lined plate or bowl. Repeat with the remaining tortilla strips.
In a second large pot add some oil and cook onions over medium-high heat. Cook onions 5-8 minutes. Add garlic cooking another minute. Sprinkle in chili powder, cumin, paprika, coriander, oregano, sprinkle of salt and pepper. Let cook for 1-2 minutes. Move onions to side and add tomato paste and chipotle in adobo cooking another minute.
Next in the pot is tomatoes, broth and bay leaves. Bring to a simmer. Cook, uncovered, for 30-40 minutes; add cilantro sprigs and epazote cooking an additional 5 minutes.
Remove the bay leaves. Using an immersion blender puree soup. Put back on heat, add corn, black beans and chicken. Bring to a simmer and let cook 1-2 minutes to heat everything through.
To serve put your garnishes into individual bowls including the tortillas. Ladle the soup into bowls. Let everyone top their soup with their favourite garnishes and eat while steaming hot.
Garnishes: 1/2 avocado diced, cilantro leaves, diced bell pepper, diced jalapeno pepper, grated cheddar cheese or monterey jack cheese, black beans, 1 lime cut into wedges