Preheat the oven to 375°F. Lightly oil a baking sheet. Place the tortilla strips in a single baking sheet; season with chili powder, salt and pepper, toss to combine, then arrange in a single layer. Bake until crisp and golden, about 10-12 minutes, tossing halfway through; set aside.
Heat olive oil in a large stockpot over medium heat. Cook the onions, green pepper and jalapeño until tender, 5-7 minutes.
Add the garlic, tomato paste, chili powder and cumin and continue to cook until garlic and spices are fragrant, about 2 minutes.
Stir in vegetable broth, crushed tomatoes, water, cilantro and a quarter of the baked tortilla strips. Reduce to a simmer and cook uncovered for 30 minutes.
Stir in quinoa, black beans and corn. Simmer uncovered, until quinoa is cooked, about 15-20 minutes.
Serve the soup with the remaining baked tortilla strips and your favorite toppings.