In a bowl, mix together the soy sauce, cornstarch, minchiu (or sherry), the aji amarillo paste, brown sugar, ginger and garlic, marinate the beef with half the mix, reserve the other half of the liquid and set aside.
Heat the oil in a heavy skillet or wok over high heat. Add the broccoli, the brussels sprouts and stir for a minute. Remove to a plate.
Allow the skillet to get very hot again. With wok spatula, add the meat in a single layer. Spread out the meat as you add it to the wok, but do not stir for a good minute. (You want the meat to get as brown as possible in as short amount a time as possible.) Toss the meat around for 30 seconds. Remove to a clean plate.
Pour the reserved sauce into the wok along with the beef broth and oyster sauce. Cook over high heat until it starts to thicken. Add the beef and broccoli back into the skillet and toss to coat. Season with salt if needed. Serve over steamed white rice.