In a medium bowl, whisk together ¼ cup soy sauce, 1 teaspoon sesame oil, 1 teaspoon granulated sugar, and ½ teaspoon ground black pepper until the sugar is dissolved. Add 1½ pounds beef sirloin cut into 2-inch strips and toss to coat; set the beef and marinade aside.
Heat 2 tablespoons vegetable oil in a large wok or skillet over medium-high heat until shimmering. Add the beef and any remaining marinade to the pan and cook, stirring, until the beef is browned, about 3–4 minutes. Transfer the beef to a bowl and set aside.
Reduce the heat to medium. Allow the liquid left in the skillet to simmer and begin to thicken, about 1–2 minutes.
Add 2 cloves garlic (minced) and 2 green onions (thinly sliced) to the skillet and cook, stirring, for 1 minute.
Add 1½ cups broccoli florets, 4 ounces cremini mushrooms (sliced), 1 red bell pepper (julienned), and 12 ounces baby corn (drained). Cook, stirring frequently, for 2–3 minutes until the vegetables are tender-crisp.
Return the cooked beef to the skillet and stir-fry everything together for about 2 minutes, until the beef is warmed through and the sauce coats the ingredients.
Remove from heat. Garnish with additional sliced green onions and sesame seeds if desired, and serve over 3 cups cooked rice.
Notes
Becky’s Tips
Storage:
Store beef stir fry in an airtight container in the refrigerator for up to 4 days or in the freezer for up to 3 months.