Prep the zucchini noodles: Spiralize the zucchinis and lay the zoodles on a clean towel. Sprinkle lightly with salt and let them sit for 10 minutes. This helps draw out excess moisture.
Slice the beef: Freeze the beef for 15 minutes to firm it up, then slice thinly against the grain.
Pat dry with paper towels and season with a pinch of salt and pepper.
Make the sauce: In a bowl, whisk soy sauce, rice vinegar, sesame oil, honey (if using), garlic, ginger, and a pinch of red pepper flakes. If you prefer a slightly thicker sauce, whisk in cornstarch until smooth.
Stir-fry the beef: Heat a large skillet or wok over medium-high heat with 1 tablespoon of oil. Add the beef in a single layer and cook 2–3 minutes, stirring just once or twice to get nice browning.
Remove to a plate when just cooked through.
Sauté the veggies: Add a bit more oil if needed. Toss in the white parts of the green onion and bell pepper. Cook 2–3 minutes until crisp-tender.
Quick-cook the zoodles: Pat the zucchini noodles dry again.
Add them to the pan and cook 1–2 minutes, just until warmed and slightly softened. Avoid overcooking to prevent sogginess.
Combine: Return the beef and any juices to the pan. Pour in the sauce and toss for 30–60 seconds, letting it coat everything and thicken slightly.
Finish and serve: Remove from heat.
Top with green onion tops, sesame seeds, and herbs. Add a squeeze of lime or a drizzle of sriracha if you like heat. Serve immediately.