In a large skillet, heat the oil over medium heat. Once the oil is hot, cook the onion for around 2-3 minutes or until fragrant. Mix in the garlic and cook for around 1 minute.
Add in the chili powder, cumin, cayenne pepper and tomato paste. Mix until the onion mixture is coated. Add in the quinoa and toast for around 1-2 minutes.
Add in the vegetable broth and bring to a boil. Once boiling, mix in the black beans. Reduce heat to a simmer. Cover and cook for 15 minutes.
Fry the tortillas on a frying pan lightly coated with oil to warm up. Fill the tortillas with the quinoa mixture and desired toppings.