Preheat oven to 220C. Cook eggplants over a medium flame either on a rack on a gas cooktop or on a barbecue, turning occasionally, until charred and tender (15-20 minutes). Halve and drain flesh-side down in a colander.
For quick quinoa crackers, combine flour, 100ml water and a large pinch of salt in a bowl and knead until smooth. Knead in quinoa and divide into 4 pieces. Roll through a pasta machine, starting at widest setting, then reduce notch by notch until dough is 4mm-thick. Place on 2 oven trays lined with baking paper and bake until golden (10-15 minutes). Set aside to cool, then break into rough crackers and sprinkle with sea salt flakes (optional).
Scoop out half the eggplant and purée in a food processor with garlic, tahini and lemon juice. Season generously and drizzle with oil. Scoop remaining eggplant from skins (discard skins) into a bowl, mash coarsely with a fork, mix in puréed eggplant, top with a dollop of yoghurt, scatter with coriander and serve with quinoa crackers.