Tzatziki, the classic Greek yoghurt, garlic and cucumber dip, comes in two categories: the good homemade stuff and the store-bought. The quality of the yoghurt and the amount of garlic are what really make the difference. But you also have to know what company tzatziki likes to keep, namely fried potatoes, lamb chops and, most importantly, golden, battered slices of courgettes and aubergines. The best places to sample this repertoire are oikogeneiakes/exohikes psistaries, or family/countryside grill houses. Greeks come to these places around Athens in droves, crowded around tables of twenty friends, children and grandparents. There is always some chunky, garlicky tzatziki on every table. We recommend Agios Merkourios, right next to the former summer palace grounds of Tatoi, ideal for a digestive stroll (or nap) among the pine trees.