Step 1 – Clean celery, removing the fibrous strings from each stick. Cut into thin strips 4 to 5 cm (2 to 3 in) long. Wash celery. Cover with cold water in a bowl and set aside.
Step 2 – Slice radishes into thin circles. Add to the bowl with the celery.
Step 3 – On a separate cutting board, peel the avocados and cut into wedges. Place avocado in a bowl with water and a little lemon juice to stop them from turning brown.
Step 4 – Strain the celery and radishes. Place them in a serving bowl and dress with lemon juice, salt and oil.
Step 5 – Stir and carefully add half the avocado.
Step 6 – Place the rest of the avocado on top of the salad and decorate with black olives.