Prepare a large non-stick skillet or hot griddle surface with sesame oil, heated on medium-high heat until sizzling, but not smoking.
In a small bowl, add all of the ingredients for the sauce. Whisk vigorously to combine until the sugar is dissolved.
Add onion and carrots, sauté for 2-3 minutes.
Add zucchini, sauté for 4-5 minutes or until the vegetables begin to form a golden-brown crust on the outside. Occasionally, give the veggies a good stir, but you don't need to sauté continuously.
Add sauce to the skillet and toss for 1-2 minutes to coat.
Sprinkle the cooked vegetables with green onion and sesame seeds.
Serve warm with hibachi steak and shrimp, noodles or rice, and yum yum sauce for dipping. Optionally, squeeze additional lemon juice over the top of the vegetables.
Notes
The goal while cooking the veggies is to get a good sear, which requires near constant contact with the pan in hot oil! If you think your veggies will be overcrowded, you can always cook them in batches.