Combine the fish, garlic, coriander, and lemon zest in a food processor. Using your hands mould the mixture into small balls and place in a steamer to steam for 7 minutes.
To make the sauce, blend all the ingredients together in a food processor until smooth. Steam the spinach. Serve the fish balls over steamed spinach with the accompanying sauce.
Note: Capers are a low kilojoule pickle which can help stimulate the production of salivary enzymes and aid digestion. To reduce the amount of salt thoroughly rinse them before eating.