We use a coarser grind and lower water temperatures (89-92C) to reduce extraction of any compounds that may come across as dry or bitter. With a more aggressive pouring technique we also reduce the coffee to water contact time giving us better control over extraction.
We use a high coffee to water ratio (20g in 38g espresso out). We pre infuse the puck for 3sec. and then extract the coffee with 7.5 bars of pressure over a total time of 19 to 22 seconds at a group head temperature of 94C.
It would be a great injustice if we talked about a Vietnamese Robusta and not talked about the Phin Filter. We use 18g of coffee ground quite coarse (15 clicks on a comandante). We pre infuse it for 35sec with 60g of water and then add another 190g at 92C. There are many ways to enjoy a Phin – black, with condensed milk or on ice.