Not a dish that photographs well, but it has a rewardingly homely quality. The scones can stand on their own or be turned into sandwiches, but make an excellent supper with the addition of the light, foamy onion purée and the poached eggs.
Heat the fat in a frying pan and cook the onion over medium heat, stirring often, until lightly browned. Remove the onion to a small bowl and cook the leek for 5 minutes without browning. Add to the onion.