In a small bowl, mix the sherry, brown sugar, cornstarch, Sriracha and ginger together with a whisk.  Pour over the sliced steak and stir to combine.  Set aside.

Heat the peanut oil in a large frying pan or wok until very hot.  Working in small batches, add the steak without crowding the pan and fry for 1 minute per side.  Remove to a clean bowl and repeat with remaining steak.

Add the broccoli to the same frying pan along with 1 cup of water.  Scrape the browned bits off the bottom of the pan and allow the broccoli to cook until just tender but still crisp.  Add the water chestnuts and stir to combine.  Add the reserved steak and any accumulated juices as well as the remaining marinade and stir to combine.  Cook just until the sauce begins to thicken, about 30 seconds.  Remove from heat and serve with steamed jasmine rice.