You can prepare the peanut sauce up to 3 days in advance. Store it in a container with a tight fitted lid in the refrigerator. When ready to use, microwave the sauce for 15-20 seconds to loosen it up.
Make sure you are using a large sheet pan for this meal. If you do not have one, use two sheet pans and rotate the pans from top to bottom, and front to back halfway through baking.
When broiling the sheet pan dinner, make sure to watch over it carefully! Things can go from a lovely golden color to burnt very quickly.
There will be excess liquid from the onions and peppers in the sheet pan when baking is complete. Don’t stress about it. Make sure you use a slotted spoon or slotted spatula to transfer the chicken and veggies to a bowl before tossing with the sesame oil and vinegar.