Preparing beef for soup
Appearance is everything in this gorgeous soup! Beautiful wispy egg whites floating in a crystal clear broth is how we truly evoke the scene of that famous Chinese landmark, West Lake.
But when you boil meat, you'll inevitably get that "scum"; the cloudy foam and debris of perfectly harmless proteins. Harmless, but not gorgeous. Keep your broth shiny and clear by rinsing the beef before marinating, and then parboiling the beef before adding it to the soup.
Don't worry about rinsing or boiling the flavor out. Rinsing gets rid of the metallic taste of excess myoglobin, and because we'll have made sure the beef is marinated well, it'll still have plenty of flavor.
Starches for thickening slurries
We often use cornstarch to create our thickening slurries. This time, we've opted for potato starch just to change it up. It's a little more powerful than cornstarch, so we need slightly less slurry to achieve the same amount of thickening compared to if we used cornstarch slurry.
Other possible starches you can use, if you have them on hand, are arrowroot and tapioca starch.
As always, whenever you create a thickening starch slurry, mix your starch of choice thoroughly in cold or cool water in a separate bowl. Once all the starch is dissolve and no lumps remain, you can pour slowly into the soup or sauce you're thickening, while continuously stirring. Stop when you've almost reached your desired consistency; the soup or sauce will thicken a bit further as it cools.