Drain soaked chickpeas, place into a large saucepan and cover with water. Bring to the boil. Simmer for 40–50 minutes until just tender. Take care not to overcook them; they should retain a bit of bite. Drain again and place in a large bowl.
Meanwhile, place the farro in a large saucepan of water, bring to the boil and simmer for 25 minutes. Drain, rinse and drain again. Spread cooked farro out on a tray to dry for ten minutes. Add to the chickpeas. Allow to cool, then stir through the red onion and parsley. Reserve ½ of the undressed chickpeas, farro, red onion and parsley (about 6 cups) for the Falafel with farro and chickpeas.
Place lemon juice, extra virgin olive oil and salt in a screw-top jar and shake well until combined. Drizzle over the remaining chickpeas, farro, red onion and parsley; add pepper, and toss gently. Arrange on a large platter.
To prepare eggplant, preheat oven to 200°C (390ºF). Season eggplant slices with the extra salt. Set aside for 10 minutes. Rinse slices with water, pat dry with a clean tea towel and brush with olive oil. Place on a large baking tray lined with baking paper. Roast for 30 minutes. Chop roughly and arrange on top of the dressed chickpeas, farro, red onion and parsley; followed by the chopped tomatoes. Drizzle with tahini sauce, and scatter with extra parsley.