Step 1Preheat oven to 220°C. Remove rind from half of the lemon. Slice rind thinly. Juice the lemon halves (you will need 2 tablespoons of lemon juice).
Step 2Place chickpeas, onion, garlic, coriander roots and stems, ground coriander, cumin, baking powder, egg white, half of the parsley and half of the lemon juice in a food processor. Blitz until mixture is finely chopped.
Step 3Line a large baking tray with baking paper. Shape level tablespoons of mixture into 16 balls. Place on prepared tray. Flatten slightly and spray with olive oil. Bake for 20 minutes, or until golden brown and warmed right through.
Step 4Meanwhile, combine tomatoes, lemon rind, coriander leaves, olive oil, remaining parsley and juice in a medium salad bowl. Combine yoghurt and tahini in a small bowl with 1 1/2 tablespoons of water and mix well, using extra water to thin out if necessary.
Step 5Serve falafels with tomato salad, rocket leaves, warm pita bread and tahini yoghurt.