Slice all of the ingredients and marinate the zucchini in the oil with garlic powder. You can marinade all of the vegetables, but I personally like to keep the rest in a more natural flavor.
Heat up your hibachi grill with your binchotan charcoal. That would, of course, be ideal. But if you don't have those, don't worry. You can also grill these veggies on any type of grill or melt butter in a pan over medium heat level.
First, add sliced onion to the grill. Make sure the slices are large enough not to fall through the grates (as with all of the vegetables). Grill them for about 3 minutes.
Add the other vegetables to the grill or pan for about 4 minutes each while the onion's been on the grill for 3 minutes. If you're using a pan or wok, and are stir-frying, make sure you fry them separately.
Finally, mix the grilled vegetables up in a bowl and add the soy sauce, teriyaki sauce, and some salt and pepper to taste. I do like to keep the broccoli with a nice bite and will often keep it separate from the mixing bowl and without sauce, just to give the dish more of a crunch.
Give it a final touch by sprinkling your sesame seeds on top.
Your vegetable hibachi is ready!