Measure 4 tablespoons of cornstarch and place in a bowl. Dip each strip of beef tenderloin in the cornstarch to coat. Lightly shake off excess corn starch. Allow beef to sit for about 10 minutes before cooking.
Heat vegetable oil in a wok or large skillet on medium-high heat. Sauté the beef strips, cooking a few at a time, until they start to crisp. This should only take a few minutes because the beef is thinly sliced.
Remove beef from pan and set aside.
Lower heat to medium and sauté garlic and ginger for about 1 minute, making sure not to burn the garlic.
Add in soy sauce, water, Worcestershire sauce, rice wine vinegar, and brown sugar. Stir to combine all of the ingredients.
As the sauce begins to thicken, add the beef back to the pan along with half of the scallions. Cook for an additional 2-3 minutes to heat through.
Serve over rice and top with remaining diced scallions.