Prep skewers if needed *

Starting with the vegetables first. Cut everything into cubes. 

For the red onion, cut off the top and bottom and cut in half from the top down. Lay the pieces down, cut them in half along the longest part and then cube them into thirds. This will keep them in the best cube shape for skewering and the biggest pieces should be around 1 inch in size.

For the peppers cut them in half, remove the seeds and the top stem. Then cube them into roughly 1 inch pieces. 

For the Zucchini, cut off the ends and split it down the middle long ways. Then cut into 1 inch  slices.

For the chicken, Cut into strips and then into cubes. You want them to be roughly the same size. Though remember chicken breast taper towards the end so you will have some thinner pieces. You can keep these pieces longer and when it comes to skewering them you can fold one end over the other and skewer it twice.

Now that everything is cubed start putting them on the skewers. You can intermix the onions and peppers if you'd like but for even cooking keep each  ingredients to it's own skewer. This will allow for more even cooking, better flavor and make grilling easier.

Drizzle or brush on the oil to all sides and salt and pepper to taste.

Heat the grill to between 425F and 450F (Medium high to High heat). Once the grill is hot lay down the skewers.

Cooking times will vary slightly depending on the size of the cuts and the grill temperature. But it usually takes only 2-4 minutes for the veggies  and 3-6 for the chicken on each side. If you'd like an allover grill (instead of just two sides) you can turn them every 2 minutes until done.

Remove the skewers from the grill as each one reaches doneness.  The zucchini will likely be done first, followed by the onion and peppers and finally the chicken. but again it all depends on how big or small you cut everything and how done you like your veggies.

Allow to rest till the skewers are cool enough to handle, then enjoy.