In a medium bowl, combine soy sauce, brown sugar, honey, rice vinegar, sesame oil, minced garlic, and grated ginger. Stir until the sugar is dissolved to create the teriyaki marinade.
Add the thinly sliced beef sirloin to the marinade and toss to coat evenly.
Transfer the beef and marinade into a freezer-safe resealable plastic bag or airtight container. Remove excess air and seal tightly.
Label the bag or container with the date and freeze for up to 3 months.
When ready to cook, thaw the beef teriyaki marinade in the refrigerator overnight.
In a small bowl, mix cornstarch and water until smooth to create a slurry.
Heat vegetable oil in a large skillet over medium-high heat.
Remove the beef from the marinade, reserving the marinade for later use.
Add the beef to the skillet and cook for 3-4 minutes until browned on all sides.
Pour the reserved marinade into the skillet and bring to a simmer.
Stir in the cornstarch slurry and cook for 2-3 minutes until the sauce thickens and coats the beef.
Remove from heat and garnish with toasted sesame seeds and sliced green onions.
Serve immediately with steamed rice or your choice of side.