Heat a saucepan that has been sprayed with oil. Add the onion and cook, stirring, until soft.
Add the beef and cook until the beef is starting to brown. Add the taco seasoning and cook, stirring, for 1-2 minutes.
Add the water, tomatoes and tomato paste and bring to the boil. Reduce heat to low and simmer, covered, until the beef is cooked, approximately 40 minutes.
Add the beans and coriander to the soup and cook, stirring occasionally, for 5 minutes or until heated through.
Remove from heat and leave to cool slightly.
Pour soup into a blender or food processor and puree until soup is thin enough to drink through a thick straw’.