Cook your base: Make your rice according to package directions. Fluff and set aside.
Steam or sauté your chosen veggies until crisp-tender. Season lightly with salt and pepper.
Whisk the teriyaki sauce: In a bowl, mix soy sauce, brown sugar, rice vinegar, mirin (if using), water or broth, cornstarch, and sesame oil. Add chili-garlic sauce if you like a kick.
Stir until smooth and no cornstarch lumps remain.
Brown the beef: Heat oil in a large skillet over medium-high. Add the ground beef and break it up with a spatula. Let it sit for 1–2 minutes to brown, then continue cooking until no pink remains and edges are caramelized.
Drain excess fat if needed.
Sauté aromatics: Push the beef to the sides. Add onion to the center and cook 2–3 minutes until softened. Stir in garlic and ginger for 30 seconds, just until fragrant.
Add and thicken the sauce: Lower heat to medium.
Give the sauce a quick stir and pour it over the beef. Stir frequently as it bubbles; it should thicken in 1–2 minutes and coat the meat. If it’s too thick, splash in water; if too thin, simmer another minute.
Taste and adjust: Add black pepper and, if needed, a pinch of sugar or a splash of vinegar.
You’re aiming for a balanced sweet-salty tang with a glossy finish.
Assemble bowls: Divide rice among 4–5 meal prep containers. Top with teriyaki beef and veggies. Finish with green onions and sesame seeds.
Cool before sealing: Let containers cool uncovered for 15–20 minutes to prevent condensation before closing and refrigerating.