- Heat a large cast iron skillet or wok over high heat. Add enough oil to coat the pan, waiting until it shimmers. 
- Add half the veggies to the pan and saute, undisturbed, for 1-2 minutes or until browned on the bottom.  Sprinkle with salt and pepper. Toss, and cook another minute or so, until the edges have browned.. Remove to a plate, then repeat with the remaining veggies. 
- Add all the veggies back to the pan, and add the garlic and butter, allowing it to cook until fragrant, about 1 minute. 
- Add the sauce and cook, stirring frequently, until the vegetables have soaked up the sauce and are crisp tender, another 2-4 minutes. Remove from heat and sprinkle with sesame seeds if desired.