Ingredients :

• Sirloin — It’s the ideal choice because it stays tender even when seared hard. Cut it very thin — 3 to 4 mm, against the grain. If the piece comes straight from the fridge, it slices much more easily than at room temperature.
• Egg noodles — Not rice vermicelli, not soba. Real thick egg noodles with a good bite. You can find them in the Asian section of most supermarkets. Cook them al dente — they will finish cooking in the sauce and absorb everything.
• Dark soy sauce — Dark soy gives that deep caramel color and a rounder flavor, less salty than acidic. Light soy works too, the result will just be a bit paler. Kikkoman or any Asian brand will do the trick.
• Lime — This is what cuts through the umami and prevents the dish from becoming heavy. A whole lime, zest included. The grated zest added off the heat at the very end really changes things — don’t skip it.