Heat the oil in the large pot over medium heat. Add the yellow onion and cook, stirring regularly for 6-7 minutes until softened.
Add the scallions, garlic and jalapeño and cook for 1 minute more. Season with salt and pepper.
Assemble the Soup:
Add the black beans, tomatoes, and stock and bring to a boil. Season with salt, pepper, chili powder, paprika, cayenne powder, and cumin. Bring to a boil and then reduce heat and simmer for 20-30 minutes until thickened.
Blend the Soup:
Taste and season the soup to your preferences. If it seems too thick, add a bit more stock or water.
Using an immersion blender or traditional blender, blend the soup to a smooth purée.
To Serve:
Ladle the soup into bowls and serve with crunchy tortilla strips. avocado, lime juice, and a sprinkle of chili powder. Enjoy!