Finely chop onion and prepare garlic for crushing.
Drain and rinse black beans thoroughly and set aside.
Heat oil in a large saucepan, then add onion and garlic. Cook for 3-4 minutes stirring frequently.
Add black beans and stir for a further 3 - 4 minutes.
Add cumin and chilli and stir until mixed in well.
Add tomatoes to the saucepan and bring to the boil.
Once it has started to boil, place on the lid, turn down and simmer for 15 minutes, stirring occasionally.
Remove from the heat and then serve with Mexican rice and fresh salsa