So I recently brewed a Vienna lager, and I noticed that the bjcp description says it should be medium to medium-light bodied but have a dry finish. I know I can control body by adjusting mash temps (higher temps for fuller body and lower temps for lighter body) and that those adjustments can also affect how sweet or dry the beer is, but how can you get a medium body with a dry finish? Well attenuating yeast?
Although not unrelated, body finish are two different aspects of a beer. Body is quite dependent on viscosity, which is determined to great extent by larger molecular-weight components. These components can include molecules that are sweet and those that are not, which affects the finish. Common practice is to use dextrine malts (carapils, e.g.) to raise body without raising sweetness. Of course, you need a yeast that will consume a most of the low molecular weight sugars and leave the dextrins intact to end up with substantial body and a dry finish. Not only mash temperature, but also mashing procedure will affect the molecular makeup of the wort and thus the body and finish. As you are interested in a Vienna lager, it wouldn't surprise me to learn that decoction would contrite to the overall character of the classic Vienna lager. I am not expert on this; perhaps someone else will chime in? Gordon Strong's book may have something to say about this.
All else equal ... i use ~5% Carafoam for added body + lower-end mash temps and ~3% table sugar to get a clean finish.
Adding gypsum to your water (in the mash or kettle) will also increase the perception of a dry finish
