Sauté the veggies: Heat oil in a large stockpot over medium-high heat. Add onion, carrots and jalapeño and sauté for 7 minutes, stirring occasionally, until softened. Add garlic and sauté for 2 additional minutes, stirring occasionally.
Add the broth ingredients: Add the chicken stock, cooked chicken, corn, diced tomatoes, green chiles, chili powder, cumin and oregano, and stir to combine. Continue cooking until the broth reaches a simmer.
Add the noodles: Reduce heat to medium-low, to maintain the simmer. Stir in the fideos (or broken-up spaghetti). Cook for 5 minutes, stirring occasionally, or until the noodles are al dente.
Season the soup: Stir in the lime juice. Taste the soup, and season with salt and pepper as needed.
Serve: Serve warm, topped with your desired garnishes.