Preheat oven to 400F. Line a baking sheet with parchment paper. Cut 3 tortillas into thin strips (about 2” long, ½” wide) and place on the baking sheet. Toss with 1 tablespoon oil and ¼ teaspoon salt until evenly coated. Spread out into one layer and bake for 10 minutes, tossing halfway, or until they turn deeply golden. Remove and let cool. They will crisp up more as they cool.
In a large pot over medium heat, add remaining 2 tablespoons oil, onion, carrot and ½ teaspoon salt. Cook until softened, about 5 minutes. Add bell peppers, jalapeno (if using), garlic, tomato paste, cumin, oregano, smoked paprika, and ½ teaspoon salt. Cook for about 30 more seconds, stirring constantly.
Add the water, tomatoes, beans, chicken, and remaining 1 teaspoon salt. Bring to a boil, then reduce heat to low and simmer gently for 15 minutes, stirring halfway, or until the chicken is cooked (160F). Remove chicken and place on your cutting board. Stir the spinach into the pot (if using), and cook until wilted. Remove from heat.
Tear up the remaining 3 tortillas and place in a blender. Transfer 2-3 cups of the soup to the blender, making sure the tortillas are submerged. Let sit for 10 minutes to soften, then blend until smooth. While the tortillas soften, shred your chicken using two forks (or chop it up). Stir the chicken and blended tortilla mixture back into the pot until smooth.
Taste and add more salt, if needed. Serve topped with a dollop of yogurt, cilantro, and tortilla strips.