Place beef in a bowl and add sherry cooking wine and cornstarch. Mix together and marinate for 15 minutes.
Meanwhile, in a separate small dish mix together 2 tablespoons of the hoisin sauce and all of the soy sauce and set aside.
When beef is ready, add remaining 1 teaspoon of hoisin sauce and mix into beef.
Heat a tablespoon of the cooking oil in a wok or skillet over high heat. Add beef and stir fry for 2-3 minutes, or until no longer pink. Don't cook too long or it will get tough! If it's still a little pink, it's okay.
Remove the beef to a bowl and return wok to the stove. Add the remaining 1/2 tablespoon of oil to the wok and stir fry the garlic, chili peppers and green onion for 2-3 minutes.
Move the vegetables to one side of the wok, add beef to the other side. Pour the soy sauce mixture into the center and stir a little then combine beef, vegetables and sauce. Stir just a minute or so to combine and serve immediately over rice or thin noodles.
While I recommend fresh cloves of garlic, you could also use jarred garlic. Do not use dried garlic.
Knowing which dried chili peppers to buy can be confusing. I usually grab whole Arbol chili peppers (Chile de árbol).
If you like, you can garnish the finished dish with sesame seeds.
Stir fry dishes should be served as soon as they are done. It's also a very quick cooking process, so you don't have time to stop in between steps to chop things. Slice, cut, chop, and measure all ingredients before you begin. It's also a good idea to get your rice going first, depending on how long it will take to cook.
If you can't handle the heat or don't like spicy foods, you can use sweet peppers or bell peppers instead of the chili peppers.