Chop the onion finely. Cut the tomato into half and remove the seeds. Cut the tomato flesh into small cubes. Remove the seeds from the red bell pepper and chop finely.

Halve the avocado, remove the pit and peel off the skin. Cut the avocado into cubes and mash with a fork into either a coarse or smoother guacamole.

Chop the coriander finely. Add the red onion, tomato, bell pepper, and coriander to the avocado. Season with lime juice and salt. Serve the guacamole in a bowl.